UNI;  if    OF 

CAtl;ORNIA 


The  eye — it  cannot  choose  but  see. 

— Wordsworth. 


Brain,  showing  eyes  with  muscles  removed,  optic  nerves,  and 
chiasm. 


TECHNIQUE 

OF 

EYE  DISSECTIONS 


BY 

FREDERIC  A.  WOLL,  Ph.D., 

Associate  Professor,  Department  of  Hygiene,  College  of  the 
City  of  New  York;  Optometry  Courses,  Columbia  University; 
Member  of  New  York  State  Board  of  Examiners  in  Optometry; 
Honorary  Member:  American  Optometric  Association;  State 
Societies — Alabama,  California,  Connecticut,  Kentucky,  Maine, 
Massachusetts,  North  Carolina,  Rhode  Island;  Local  Societies — 
Lehigh  F alley  Society  of  Optometrists,  Mahoning  Valley  Opto- 
metrists' Society,  and  Optometrists'  Club  of  Brooklyn. 


SECOND  EDITION 


NEW  YORK 

FREDERIC  A.   WOLL 
1924 


OPTOMETRY  LIBRARY 

COPYRIGHT,  1914,  BY 

FEEDEEIC    A.    WOLL 

Printed  in  the  United  States  of  America 

First  Edition,  July,  1914 
Second  Edition,  April,  1924 

OPTOMETRY  LIBRARY 


SCHLUETER   PRINTING   CO..    NEW  YORK 


LIBRARY 


DEDICATION 

THIS    LITTLE    BOOK   IS   DEDICATED   WITH    AFFEC- 
TION AND  ESTEEM  TO  MY  FIRST  TEACHER 
IN  OPTICS,  MY  FRIEND  FOR  YEARS 

ANDREW  JAY   CROSS 

WHOSE    RESEARCH    IN    THE    FIELD    OF    APPLIED 

OPTICS  HAS  WON  FOR  HIM  RECOGNITION 

AND  HONOR 


\  A 


CONTENTS 


PAGE 

Preface         ...    J.  -  38     . .      13 

Introduction         17 

Removal  of  Hyaloid  Membrane  with  Contents  and  Attach- 
ments Intact       25 

Canal  of  Petit,  The 35 

Interior  of  the  Eye,  The 38 

Posterior  Half ,  The %  .      ..      ..      ..      . .     :40 

Optic  Nerve,  The       ..      ..      '..,'..      ....      ...      .  .    =47 

Anterior  Half,  The   ..      ..      ..    f . . "  .~.      ..     ....      .:.;:!ili» 

Iris,   The      .'....... VMifil 

Cornea,   The     >;.     .. ..52 

Crystalline  Lens,  The .  .      53 

Choroid,  The       62 

Retina,    The .  •      74 

Sagittal  or  Vertical  Section  of  the  Eye,  The 86 

Papilla,  Puncta  Lacrimalia,  and  Nasal  Duct,  The   .  .      .  .     92 

Meibomian  Glands  and  Ducts,  The        96 

Enucleation  of  the  Orbital  Contents,  The 97 

Ophthalmoscopic  Examinations ..   106 

Lacrimal  Ducts,  The         . .      . .      .  f     . .      112 

Lacrimal  Gland,   The        ......      114 

Capsule  of  Tenon,  The 115 

Superior  Oblique  Muscle  and  its  Pulley 117 

Other  Extrinsic  Muscles,  The 118 

Three   Tunics   of  the   Eye,   the   Hyaloid   and  its   Attach- 
ments, The 120 


ILLUSTRATIONS 


PAGE 
Brain  showing  eyes  with  muscles  removed,  optic 

nerves,  and  chiasm Frontispiece 

Glassware  and  tools 22 

The  first  cut        28 

How  the  point  of  the  scissors  is  kept  away  from  the  under- 
lying tissues        29 

Half  of  the  sclerotic  separated        30 

Picking  up  the  choroid 31 

Emptying  the  eye  of  its  contents 32 

Isolated  hyaloid,  contents  and  attachments  intact    .  .      .  .  33 

Petit 's   Canal      36 

Cutting    eye    into    anterior    and    posterior    sections    with 

safety-razor  blade       39 

Posterior  half  showing  retinal  vessels  and  choroid    .  .      .  .  40 

Showing  network  of  vitreous 42 

Tearing  retina  away   from  posterior   half   of   eye    .  .      .  .  44 

Posterior  half  of  eye  with  retina  removed 45 

Excavated  posterior  half   of  eye 46 

Split  optic  nerve        47 

Ciliary  processes  and  the  lens        48 

How  to  pull  off  vitreous 50 

Processus  Zonuloe      54 

Onion-like  layers  of  lens  removed  .  .      56 

Cross  section  of  lens        57 

Lenses  showing  the  results  of  different  kinds  of  treatment  60 

Puncturing  the  cornea 63 

Removing  the  cornea        64 

How  to  separate  the  choroid  from  the  sclerotic 65 

Cutting  away  the  separated  sclerotic 67 

Scraping  the  choroid  free  from  the  sclerotic       68 

The  isolated  choroid          69 

Inserting  scalpel  to  loosen  lens  and  cut  through  vitreous  70 

Ta.king  out  lens  and  "core"  of  vitreous 71 

Squeezing  out  remaining  part  of  vitreous 72 

Cutting  through  the  iris 75 

Cutting  around  the  ciliary  ring 76 

11 


ILLUSTRATIONS 

PAGE 

Lens,  iris,  and  part  of  vitreous  removed 77 

How  to  force  blowpipe  into  the  vitreous 78 

Bulging  out   of  vitreous   caused  by  blowing  air  through 

glass  blowpipe 79 

Showing  vitreous  removed       80 

Folding  the  retina  by  blowing  air  at  it  through  blowpipe     81 
Suspended  retina.     Sclerotic  ready  to  be  cut  away  . .      .  .     82 

Showing  sclerotic  nearly  all  cut  away 83 

Isolated  retina 84 

The  beginning  of  the  cutting  of  the  eye  for  sagittal  sec- 
tions       87 

Method  of  cutting  through  the  crystalline  lens 88 

Cutting  through  cornea  to  complete  the  sagittal  sections     89 

Sagittal    section   enlarged        90 

Part  of  calf's  head  showing  knitting  needles  inserted  in 

puncta          93 

Course    of    knitting    needles    showing    the    course    of    the 

canaliculi      94 

Initial  cuts  to  be  made  in  the  skin         98 

First  cut  in  bones  of  orbit 99 

All  the  cuts  to  be  made  in  bones  of  orbit 100 

How  to  pry  bone  loose 101 

Dissecting  close  to  bones  of  orbit 102 

Excavated  orbit         103 

Anterior  view  of  enucleated  eye 104 

Side  view  of  enucleated  eye.     All  parts  in  situ 104 

Enlarging  pupil  for  ophthalmoscopic  inspection        .  .      .  .   107 

How  to  get  rid  of  the  pucker  in  the  cornea 108 

Window  cut  in  the  eye     . .      110 

Pins  inserted  in  lacrimal  ducts       112 

Capsule  of  Tenon  blown  up 115 

Showing  the  extrinsic  muscles  of  the  eye 118 

Cutting  through  the  iris 120 

Scraping  ciliary  processes  free.    Choroid  cut  around  ciliary 

ring       121 

Cutting  away  choroid        122 

Three  tunics,  hyaloid,  and  lens       123 


12 


PEE  FACE 

THE  aim  of  this  booklet  is  to  present  to  the 
eye-specialist,  the  teacher,  the  student,  and 
others  interested  in  the  study  of  the  anatomy 
and  physiology  of  the  eye,  some  definite  meth- 
ods to  follow  in  the  dissection  of  that  organ. 

Most  dissections  of  the  eye  are  not  made 
with  the  same  degree  of  care  and  skill  used  in 
the  dissections  of  other  organs.  In  follow- 
ing the  usual  method  of  dissecting  eyes,  much 
of  the  important  detail  is  lost.  Often  certain 
membranes  are  confounded  with  others,  and 
wrongly  demonstrated.  Furthermore,  an  eye 
is  merely  divided  by  some  demonstrators  into 
an  anterior  and  a  posterior  half,  a  very  short 
time  is  spent  by  the  students  scrutinizing  each 
half;  then  the  text-book  is  turned  to,  and  the 
anatomy  is  studied  descriptively. 

Not  enough  time  has  been  given  to  thorough- 
ly dissecting  all  parts  of  the  eye.  As  much 
time  should  be  given  as  is  necessary  to  bring 

13 


PREFACE 

out  prominently  all  its  parts.  Other  organs  of 
the  body  are  more  thoroughly  dissected,  and, 
therefore,  the  student  has  better  opportunity 
to  gain  a  clearer  comprehension  and  better  un- 
derstanding of  the  anatomy  and  physiology  of 
those  organs.  Also,  as  much  time  should  be 
given,  proportionately,  to  the  learning  of  the 
technique  of  the  dissection  of  the  eye  as  is 
given  to  the  learning  of  the  technique  of  dis- 
secting other  organs  of  the  body. 

Many  now  make  a  direct  specialty  of  minis- 
tering to  those  suffering  from  errors  of  ocular 
refraction,  ocular  diseases,  and  ocular  reflexes, 
and  for  those  specialists,  principally,  this  book 
is  written.  It  is  to  fulfil  its  mission  to  them  by 
acting  as  a  guide  and  as  a  complement  to  the 
descriptive  matter  in  the  text-book.  It  is  sent 
forth  in  the  hope  that  it  will  tend  to  create 
more  interest  in  the  study  of  the  practical 
anatomy  of  the  eye.  It  is  written  with  a  de- 
sire to  stimulate  the  ability  to  make  careful 
and  intelligent  observation.  It  carries  with  it, 
as  a  final  end,  an  earnest  wish  that  it  may,  in 
pome  small  way,  be  the  means  of  opening  up 

14 


PREFACE 

to  the  original  researcher,  a  larger  field  for 
the  further  study  of  the  most  important  of  the 
senses — the  eyesight. 

Most  of  the  dissections  explained  in  the  fol- 
lowing pages  are  original;  some,  however,  are 
only  revisions  of  old  methods. 

This  opportunity  is  taken  to  acknowledge 
the  many  helpful  suggestions  that  were  made 
by  Dr.  Ivin  Sickels,  of  the  College  of  the  City 
of  New  York,  and  by  the  late  Dr.  Edward  C. 
Spitzka,  of  New  York.  Thanks  are  due  Mr. 
E.  F.  Howes,  of  Messrs.  Swift  &  Co.,  for  fur- 
nishing the  necessary  supply  of  beef  eyes; 
to  Messrs.  Lee  &  Beach,  photographers,  of 
New  York,  for  their  painstaking  efforts  in  pro- 
ducing good  photographs  of  the  actual  dissec- 
tions; and  to  Schlueter  Printing  Company,  of 
New  York,  for  their  many  courtesies  and  in- 
terest in  the  production  of  the  book. 

FREDEKIC  A.  WOLL. 
New  York,  July  21,  1914. 


15 


INTRODUCTION 

IN  eye  dissections  it  is  unnecessary  to  have 
either  a  large  equipment  of  instruments  or 
a  special  room.  To  have  a  laboratory  at 
one's  disposal  is  but  a  small  added  conve- 
nience. Not  to  have  it,  is  no  serious  hindrance. 
The  work  may  be  carried  on  and  successfully 
done  in  one's  office  or  in  the  home,  as  well  as 
in  class-room  or  laboratory.  If  it  is  true  that 
the  atmosphere  of  a  laboratory  adds  zeal  to 
the  efforts  of  a  worker,  but  there  is  no  labora- 
tory available,  then  reverse  the  order;  let  the 
zeal  of  the  worker  add  to  the  atmosphere  of 
the  place  in  which  he  is  doing  his  work. 

Two  things,  among  others  to  be  mentioned 
later,  are  essential;  a  table  of  convenient 
height,  and  a.  good  light,  natural  or  artificial. 
Both  are  but  modest  needs.  Compared  with 
other  dissections,  there  will  be  found  an  ab- 
sence of  offensive  odors.  Neither  are  there 
any  repulsive  sensations  experienced.  Such 
experiences  are  quite  common  when  making 

17 


INTRODUCTION 

other  kinds  of  dissections.  This  work  is 
clean  and  attractive.  Indeed,  one  may  even 
develop  a  rather  keen  sense  of  the  aesthetic. 
Many  of  the  various  parts  of  the  ,eye,  when 
separated  and  properly  preserved,  then  viewed 
and  inspected,  are  bound  to  bring  forth  ex- 
clamations of  appreciation  and  wonderment. 
One  can  then  better  understand  the  state- 
ment: "When  Nature  perfected  the  first  eye 
she  took  a,  day  off  so  she  could  admire  the  re- 
sult of  her  finest  piece  of  handiwork." 

This  does  not  imply  that  dissections  of  the 
eye  tend  to  develop  art  appreciation.  Appre- 
ciation of  the  wonderful  in  Nature's  construc- 
tion of  the  special  organs  is  not,  however,  to 
be  relegated  to  a  distant  point.  Such  appre- 
ciation is  concomitant  with  the  knowledge 
that  comes  from  having  seen,  handled,  and 
examined  the  object  studied. 

The  orchestra  leader  must  have  a  good  lis- 
tening and  hearing  ear.  This  is  developed  in 
him  because  he  has  to  exercise  constantly  his 
power  of  listening  and  hearing.  The  dissector 
who  would  become  proficient  in  eye  dissections 

18 


INTRODUCTION 

and  in  anatomical  investigations  must  have  a 
good  seeing  eye  and  a  dextrous  hand.  To  ac- 
quire these  two  most  valuable  aids  necessary 
to  carry  on  careful  inquiry  or  research,  it  is 
essential  to  practise  using  the  eye  and  the 
hand.  Combined  with  the  expertness  of  these 
two,  must  be  the  ability  to  continue  one's  ef- 
forts in  the  face  of  failure ;  to  redouble  one 's 
efforts  to  attain  success  despite  the  short- 
comings of  eye  or  hand.  This  simply  means 
practise  and  patience.  And  the  one  who  is 
without  that  wonderful  virtue,  patience,  will 
never  stay  long  enough  with  his  problem  to 
gain  either  'an  observing  eye  or  an  expert 
hand,  or  to  achieve  his  end,  and  thereby  reap 
the  full  and  pleasing  results  of  his  efforts.  In 
order  of  importance,  patience  really  precedes 
dexterity,  skill,  arid  observation;  and  persis- 
tence of  effort  is  a  factor  not  to  be  entirely 
outshone  by  any  other  virtue.  With  these  at- 
tributes, knowledge  of  the  subject  in  hand 
naturally  follows. 

One  reason  why  eye  dissections  are  easily 
carried  on  is  because  material  can  always  be 

19 


INTRODUCTION 

readily  procured.  Any  butcher  will  furnish 
sheep,  pig,  or  beef  eyes.  Or,  if  one  has  the 
time  to  visit  the  manager  of  a  slaughter-house, 
and  make  known  to  him  one's  needs,  he  will 
supply  enough  eyes  to  carry  through  a  host 
of  interesting  dissections  and  experiments,  and 
give  sufficient  material  for  careful,  orderly, 
and  fruitful  study.  Perhaps  in  no  other  kinds 
of  dissections  will  the  investigator  find  so 
much  of  interest,  or  have  his  efforts  crowned 
with  such  abundant  and  satisfactory  results, 
as  in  the  dissections  of  the  eye.  But  no  one 
should  try  to  study  all  parts  of  the  eye  with 
only  one  specimen.  To  try  to  do  so  is  an  error, 
and  a  common  one  often  committed  by  both 
teachers  and  students.  Specimens  cost  little 
or  nothing,  and  it  is  no  more  trouble  to  pre- 
pare a  half-dozen  eyes  for  dissection  than  one. 
The  cost  of  preparation,  too,  is  but  little  more 
for  a  number  of  eyes  than  it  is  for  one,  and 
may  be  no  more  in  some  instances.  Besides, 
having  enough  material  on  hand  saves  time  in 
case  of  a  failure.  Also,  one  can  quickly  repeat 
a  dissection,  and  so  procure  any  number  of 

20 


INTRODUCTION 

desired  specimens  of  specific  parts,  or  do  over 
again  the  same  dissection  on  another  eye  just 
for  the  purpose  of  practise,  and  thus  add  to 
one's  dexterity.  It  is,  therefore,  strongly  ad- 
vocated to  have  plenty  of  material  on  hand  be- 
fore beginning  work.  Economy  here  is  not 
even  " penny  wise." 

The  tools,  or  instruments,  needed  are  but 
few  in  number;  an  ordinary  scalpel,  a  pair  of 
blunt  tweezers,  or  forceps,  as  they  are  some- 
times called;  a  pair  of  sharp-pointed  tweezers, 
a  pair  of  small,  sharp-pointed  scissors  of 
about  three  to  three  and  a  half  inches  in 
length,  and  a  pair  of  large  scissors,  about 
four  or  five  inches  in  length,  having  one  jaw 
sharp-pointed  and  one  jaw  blunt. 

For  glassware,  any  wide-mouthed  jar  or 
bottle,  such  as  the  ordinary  fruit  or  jelly  jar, 
will  do  for  preparing  material.  For  clarifying 
tissues,  or  for  preserving  and  keeping  them, 
small,  wide-mouthed  bottles  or  vials  should  be 
used.  And  for  temporary  keeping,  or  for 
purposes  of  "running  through"  various  fluids, 
the  regular  Stender  dishes  are  most  conve- 

21 


INTRODUCTION 

nient.  A  glass  graduate  is  almost  indispen- 
sable if  accuracy  in  measuring  fluids  is  de- 
sired. (Fig.  1.) 

The  chemicals  needed  are  few  in  number 
and  small  in  quantity:  Alcohols  in  varying 
strength,  which  can  be  made  by  diluting  a  95 


Fig.  1. 

per  cent,  alcohol,  and  keeping  an  absolute  alco- 
hol on  hand.  A  few  ounces  of  formaldehyde 
will  make  enough  solutions  of  different 
strengths  to  be  sufficient  for  the  preparation 
and  keeping  of  many  specimens.  Of  other 
chemicals,  such  as  xylol  and  cedar  oil,  only 
small  quantities  are  needed;  enough  to  cover 

22 


INTRODUCTION 

a  specimen.  Fifteen  to  twenty  cents  worth  of 
each  will  be  an  ample  supply  to  keep  on  hand. 
All  of  these  may  be  procured  at  any  large 
drug  store,  and  are  the  only  chemicals  re- 
quired for  doing  the  dissections  as  explained 
in  this  book. 

Before  further  advance  is  made,  it  will  be 
best  to  state  that  this  work  deals  only  with 
methods  for  dissecting  the  various  parts  of  an 
eye,  and  is  primarily  intended  to  aid  in  the 
study  of  the  anatomy  and  physiology  of  the 
eye  by  being  used  in  conjunction  with  such 
books  as  "Gray's  Anatomy,"  "A  Text-Book 
of  Physiology,"  by  Howell,  "The  Anatomy 
and  the  Physiology  of  the  Eye, ' '  by  Brown  and 
Zoethout,  and  similar  other  works  of  authority. 
However,  if  it  is  desired  to  acquire  only  speci- 
mens, then,  of  course,  no  other  works  are 
necessary,  and  the  matter  contained  herein  is 
sufficient  to  enable  one  to  procure  just  what  is 
wanted. 

It  is  also  wise  to  state  here  that  since  hu- 
man eyes  are  hard  to  procure,  and  not  avail- 
able in  large  quantities,  one  must  resort  to  the 

23 


INTRODUCTION 

use  of  the  eyes  of  animals,  which  are  procur- 
able in  large  quantities,  and  which  may  be 
used  without  "feelings"  in  the  matter. 
Though  there  is  a  difference  between  the  eyes 
of  human  beings  and  the  eyes  of  other  ani- 
mals, the  difference  is  slight  and  of  minor  im- 
portance when  compared  with  the  similarity 
of  the  more  important  parts. 


24 


TECHNIQUE 
OF     EYE     DISSECTIONS 


REMOVAL     OF     THE     HYALOID     MEM- 
BRANE WITH   CONTENTS   AND 
ATTACHMENTS  INT  ACT*  t 

ONE  of  the  easiest  and  most  satisfactory  dis- 
sections to  attempt  is  the  isolating  of  the  hya- 
loid membrane  with  its  contents  and  its  at- 
tachments. The  success  one  meets  with  in 
making  this  dissection  will  surely  prove  a 
strong  incentive  for  making  all  the  rest.  For 
these  reasons  this  has  been  placed  first  in  this 
arrangement. 

In  eye  dissections  it  is  quite  customary,  in 
giving  directions  for  dissections,  merely  to 


*Approved  as  an  original  article  in  The  Anatomical 
Eecord,  September,  1912. 

tThis  dissection,  and  several  of  the  following,  appeared 
in  The  Optical  Journal  and  Review,  beginning-  with  the 
issue  of  January  16,  1913. 

25 


TECHNIQUE    OF    EYE    DISSECTIONS 

mention  the  hyaloid  membrane  and  its  rela- 
tions with  other  parts  of  the  eye.  Rarely  is 
there  any  attempt  made  to  isolate  it.  Often, 
too,  the  retina  is  mistaken  for  the  hyaloid,  and 
the  retina,  then  wrongly  demonstrated  as 
being  attached  to  the  choroid.  Of  course,  it  is 
impossible  to  separate  the  hyaloid  from  the 
vitreous;  but  a  dissection  can  be  made  which, 
when  placed  in  a  glass  of  some  kind,  will  show 
the  hyaloid.  If  the  following  simple  tech- 
nique is  carefully  observed,  the  membrane, 
with  all  its  connections,  can  be  easily  sepa- 
rated from  certain  other  parts  of  the  eye. 
Opportunity  for  thorough  study  and  observa- 
tion will  then  be  made  extremely  easy. 

Procure  the  eye  of  either  a  sheep  or  a  bul- 
]ock.  Instead  of  following  the  usual  procedure 
of  hardening  in  any  one  of  the  several  solu- 
tions used  for  the  purpose  of  toughening  the 
ocular  tissues,  place  the  eye  in  a  cool  place 
and  permit  it  to  collapse  a  trifle.  Usually  two 
or  three  days  is  a  sufficient  length  of  time  to 
accomplish  the  result. 

Experiments  have  shown  that  if  an  eye  is 
26 


TECHNIQUE    OF    EYE    DISSECTIONS 

too  fresh  the  ciliary  processes  will  not  be 
easily  detached  from  the  hyaloid  (zonular  pro- 
cesses), and  if  the  eye  has  been  in  a  preserv- 
ing fluid,  the  same  result  will  follow.  A 
sheep's  eye  will  make  a,  better  specimen  even  if 
it  is  small,  because  the  ciliary  processes  are 
more  easily  separated  from  the  zonular  pro- 
cesses. If  a  bullock's  eye  is  used,  it  must  be 
left  in  a  cool  place  a,  day  or  two  longer  than 
in  the  case  of  a  sheep's  eye,  in  order  to  permit 
a  long  enough  time  to  elapse  to  allow  disin- 
tegration of  the  eye  to  take  place  sufficient  to 
have  the  two  processes  separate  easily  and 
cleanly. 

With  a  pair  of  dissecting  forceps  pinch  up 
the  sclerotic  about  5  mm.  anterior  to  the  equa- 
tor. With  a  pair  of  small,  fine-pointed  scis- 
sors, make  an  incision.  (Fig.  2.)  Next  hold  the 
eye  in  the  left  hand  without  exerting  any  pres- 
sure. Insert  the  point  of  the  scissors  into  the 
incision  which  has  been  made,  and  cut.  Be 
careful  to  keep  the  point  of  the  scissors  close 
to  the  sclerotic  or  an  untimely  puncturing  of 
the  choroid  will  occur.  (Fig.  3.)  Continue  the 

27 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  2— Making  the  first  cut.     (Page  27.) 


28 


TECHNIQUE    OF    EYE    DISSECTIONS 

cutting  on  a  line  parallel  to  the  equatorial  me- 
ridian and  about  5  mm.  anterior  to  it  until 
about  half  the  sclerotic  has  been  separated. 
In  cutting,  always  move  the  point  of  the  scis- 


Fig.  3 — Showing  how  the  point  of  the  lower  jaw  of  the  scissors 
is  to  be  kept  away  from  the  underlying  tissues.  (Page  27.) 

sors  forward  with  a  slight  oscillating  lateral 
movement.  (Fig.  4.)  While  doing  this,  partly 
suspend  the  eyeball  from  the  point  of  the  scis- 
sors. Doing  these  things  will  tend  to  loosen 

29 


TECHNIQUE    OF    EYE    DISSECTIONS 

the  choroid  from  the  sclerotic  and  prevent 
puncturing  too  soon  the  former  mentioned 
membrane.  Now  apply  pressure  in  such  a 


Fig.  4 — Showing  about  half  of  the  sclerotic  separated.  (Page  29.) 

manner  that  the  lips  of  the  cut  sclerotic  will 
gap.  Into  this  put  the  point  of  the  scissors 
and  very  carefully  pick  up  the  ehoroid  and  the 
retina  with  the  point  of  the  scissors  and  cut 

30 


TECHNIQUE    OF    EYE    DISSECTIONS 

them.  (Fig.  5.)  If  the  choroid  alone  has  been 
picked  up  and  separated,  the  retina  will  show 
milky  white  or  yellowish  white  underneath. 
The  retina  must  then  also  be  separated.  Care 


Fig.  5. — Picking  up  the  choroid  with  the  point  of  the  scissors. 

must  be  taken  not  to  go  deeper  than  the  retina 
or  the  hyaloid  may  be  damaged.  Continue  the 
cutting  of  the  choroid  and  the  retina  for  a 
distance  of  about  20  mm.  Apply  enough  pres- 
sure occasionally  so  that  the  vitreous  will  be 

31 


TECHNIQUE    OF    EYE    DISSECTIONS 

forced  upward  and  above  the  cut  choroid  and 
the  retina.  This  will  show  whether  any 
strands  of  the  two  membranes  have  been  left 


Fig.  6— A.  Hyaloid,  vitreous,  and  lens  ready  to  drop  out  of  the 
eyeball.    ' 

uncut.  If  the  separation  is  complete  for  the 
distance  specified  above,  invert  the  eyeball, 
squeeze  and  shake  gently  over  some  receptacle, 
such  as  a  Stender  dish,  three-fourths  filled 

32 


TECHNIQUE    OF    EYE    DISSECTIONS 

with  a  2l/2  or  5  per  cent,  solution  of  formalde- 
hyde, and  the  hyaloid  membrane  containing 
the  vitreous,  its  attachments,  suspensory  lig- 


A 


Fig.  7 — Photograph  of  dissected  hyaloid  mem- 
brane (A),  with  pigmented  indentations 
of  the  ciliary  processes,  the  suspensory 
ligament  (B),  and  the  crystalline  lens  in 
its  capsule  (C).  (Page  34.) 

ament  to  the  lens  capsule,  and  lens,  will  drop 
out  intact,  as  when  one  empties  the  contents 
of  an  egg.  (Fig.  6.) 

Many  times  a  considerable  amount  of  pig- 
ment from  the   second  tunic  will  remain  at- 


TECHNIQUE    OF    EYE    DISSECTIONS 

tached  to  the  processus  zonuloe.  This  pigment 
may  be  easily  removed  by  scraping  it  off 
with  the  sharp  edge  of  the  scalpel  or  by 
brushing  it  off  with  a  soft,  wet  tooth-brush. 

It  is  unwise  to  use  alcohol  as  a  preservative 
because  it  produces  an  almost  immediate 
opaqueness  and  hardness  which  spoils  the 
specimen  for  further  study. 

This  description  may  give  the  impression 
that  the  dissection  is  a  lengthy  one;  however, 
it  can  be  done  by  an  expert  in  two  or  three 
minutes;  by  a  beginner  in  five  or  six  minutes. 

For  purposes  of  demonstration  or  study  the 
specimen  should  be  placed  in  a  small  bottle  or 
a  vial  containing  a  5  per  cent,  solution  of 
formaldehyde.  It  can  then  be  examined  with 
hand  lens  or  microscope.  (Fig.  7.) 


34 


THE   CANAL   OF   PETIT 

THE  canal  of  Petit  is  a  "triangular  space 
around  the  circumference  of  the  lens."  That 
it  can  be  "inflated  through  a  fine  blowpipe  in- 
serted through  the  suspensory  ligament, "  is 
the  usual  direction  given.  However,  the  ordi- 
nary "fine  blowpipe"  is  much  too  large  and 
too  dull  to  be  inserted  through  the  suspensory 
ligament.  Take  a  long  medicine-dropper  (5 
or  10  cents  at  a  drug  store),  or  a  pipette, 
and  heat  it  until  it  is  red  hot  over  an  alcohol 
lamp  or  a  Bunsen  burner;  hold  one  end  with 
one  hand  and  the  other  end  with  a  pair  of 
tweezers.  As  the  glass  becomes  white  hot 
pull  the  tube  apart.  This  will  leave  the  places 
of  separation  pointed  and  sharp-edged.  Use 
the  larger  of  the  two  pieces.  Sometimes  the 
point  or  tapering  end  of  the  tube  is  too  long 
and  the  bore  too  small.  All  that  is  necessary 
is  to  first  mark  off  with  a  file  the  length  to  be 
broken  off,  and  then  that  length  may  be  snap- 

35 


TECHNIQUE    OF    EYE    DISSECTIONS 

ped  off,  leaving  a  sharp-edged,  tapering  point. 

After  having  completed  the  first  dissection 

(the  hyaloid,  contents  and  attachments),  and 

the   specimen  has  been   in   the   formaldehyde 


Fig.  8 — A.  Glass  blowpipe.     B.  Petit 's  canal. 

solution  for  ten  days  or  two  weeks,  it  will  have 
become  hard  and  tough  enough  to  stand  a 
considerable  amount  of  rough  handling.  If 
the  specimen  has  been  kept  in  a  large  recepta- 
cle, such,  for  instance,  as  a  jar,  remove  it  with 

36 


TECHNIQUE    OF    EYE    DISSECTIONS 

a  spoon;  if  in  a  small  jar  or  vial,  empty  out 
the  fluid,  then  slide  the  specimen  out  on  what- 
ever has  been  prepared  to  receive  it.  Turn  it 
so  that  the  lens  will  be  uppermost.  Find  the 
suspensory  ligament  in  the  Zone  of  Zinn.  In- 
sert the  pointed  end  of  the  glass  tube,  close  to 
the  lens,  and  blow  gently  until  the  canal  shows 
its  sacculated  construction  by  filling  with  air, 
giving  the  appearance  of  a  lot  of  little  bubbles 
surrounding  the  periphery  of  the  lens.  (Fig. 
8.)  It  may  be  necessary  to  move  the  blow- 
pipe in  and  out  in  order  to  find  the  canal,  all 
the  while  blowing  steadily  through  the  tube. 


THE  INTERIOR  OF  THE  EYE 

FOR  the  study  of  the  interior  of  the  eye  and 
its  contents  in  situ  either  a  fresh  or  a  har- 
dened eye  will  do;  a  hardened  eye  is  prefer- 
able. In  the  dissection  for  isolating  the  hya- 
loid membrane,  vitreous,  lens,  and  other  parts, 
the  anterior  and  posterior  halves  of  the  evacu- 
ated eye  may  be  separated  entirely,  and  each 
half  studied.  However,  the  choroid  and  the 
retina  will  be  more  or  less  mutilated,  and  the 
vitreous  and  other  parts  will  be  removed.  The 
absence  of  these  parts  will  prevent  one  from 
receiving  a  definite  idea  of  their  anatomical 
relationships.  Therefore,  it  is  better  to  work 
with  an  entire  and  complete  eye. 

Remove  all  the  muscles  and  fatty  tissues 
from  the  outside  of  the  globe;  then  cut  it  in 
half  through  the  equator,  thus  dividing  it  into 
an  anterior  and  a  posterior  half.  The  cutting 
of  the  sclerotic,  as  well  as  the  underlying  tis- 
sues and  the  vitreous,  should  be  done  with  the 

38 


TECHNIQUE    OF    EYE    DISSECTIONS 

large  scissors;  using  a  knife  or  scalpel  will 
tend  to  disturb  the  positions  of  those  tissues 
or  so  tear  them  that  they  will  not  be  of  much 


Fig.  9 — Showing  method  of  cutting  eye  into  anterior  and  pos- 
terior sections  with  safety -razor  blade. 

use  for  purposes  of  study.  An  ordinary  safety- 
razor  blade  makes  an  excellent  instrument  for 
separating  the  eye  into  two  halves,  because  it 
cuts  through  the  tissues  without  tearing  them 
in  any  way.  (Fig.  9.)  The  rather  dark  col- 

39 


TECHNIQUE    OF    EYE    DISSECTIONS 

ored,  viscid  fluid  that  escapes  when  the  eye  is 
halved  is  the  perichoroidal  lymph,  not  the 
aqueous,  as  is  sometimes  stated. 

THE   POSTERIOR  HALF 

The  posterior  half  is  taken  first  because  it 


Fig.  10 — The  retina,  retinal  vessels,  and 

iridescent  choroid  showing  through 

the  vitreous. 

is  the  simplest  and  easiest  of  the  two  halves 
to  dissect.  In  this  half  of  the  eye  the  retina 
may  be  readily  seen  through  the  vitreous ;  the 
choroid  and  its  apparent  iridescent  colors 
through  both  vitreous  and  retina.  (Fig.  10.) 

40 


TECHNIQUE    OF    EYE    DISSECTIONS 

Remove  the  vitreous  by  simply  tilting  this 
half  of  the  eye,  and  with  the  finger  push  out 
the  vitreous. 

Sometimes  the  vitreous  will  adhere  very 
closely  to  the  retina.  This  occurs  especially 
when  the  eye  has  been  in  formaldehyde  for  a 
long  time.  In  such  a  case  the  removal  of  the 
vitreous  without  injuring  the  retina  requires 
patience  and  care.  The  use  of  the  scalpel  and 
the  scissors  may  become  necessary.  Another 
very  good  way  to  remove  the  vitreous  is  to 
take  hold  of  the  sclerotic,  turn  it  so  that  the  vit- 
reous is  downward,  and  then  shake  gently  until 
the  vitreous  separates  itself  from  the  retina 
and,  drops  out.  After  the  vitreous  has  been 
removed,  notice  its  glassy  appearance;  hence 
its  name — hyaloid  body.  Try  to  pull  it  apart 
with  the  fingers,  and  it  will  be  noticed  that  it 
seems  to  be  held  together  by  more  or  less  of  a 
network  of  fibres.  (Fig.  11.) 

Whichever  method  for  removing  the  vitreous 
is  followed,  the  retina  will  be  left  rather  badly 
wrinkled  and]  out*  of  place.  If  the  last-men- 
tioned method,  which  is  really  the  best  of  the 

41 


TECHNIQUE    OF    EYE    DISSECTIONS 

three  described,  is  the  one  adopted,  the  retina 
will  be  left  in  an  entirely  collapsed  and  folded 
form.  In  any  case,  to  straighten  out  the  ret- 


Fig.  11 — Showing  how  vitreous  seems  to  be  held 
together  by  a  network  of  fibres.     (Page  41.) 

ina  against  the  choroid,  immerse  the  whole 
posterior  half  in  water,  inside  uppermost.  The 
retina  will  then  slowly  unfold  itself  and  lie 
flat  against  the  choroid.  With  the  tweezers  re- 

42 


TECHNIQUE    OF    EYE    DISSECTIONS 

move  the  whole  half  from  the  water ;  tilting  it 
slowly  to  empty  it  of  all  the  water,  and,  having 
done  so,  turn  it  idown  upon  the  table  rather 
forcibly  in  order  to  help  it  drain  itself  of  all 
the  water. 

Notice  the  thinness  of  the  retina,  and,  also, 
that  the  seeming  iridescence  of  the  choroid 
shows  through.  The  optic  disc,  which  is  the 
point  of  entrance  of  the  optic  nerve,  and  the 
optic  cup  are  easily  recognized,  though  neither 
will  be  seen  us  large  as  when  viewed  in  the 
living  eye  with  an  ophthalmoscope.  The 
blood  vessels  of  the  retina,  as  they  ramify 
outward  or  forward,  after  their  entrance 
through  the  optic  nerve  through  which  they 
pass,  are  also  very  plainly  seen.  A  closer 
inspection  will  show,  in  the  very  centre  of 
the  "  entrance "  of  the  optic  nerve,  a  whitish, 
pointed  vessel,  about  1  or  2  mm.  long. 
That  is  the  sloughed-off  and  atrophied  end 
of  the  hyaloid  artery,  which,  when  the  eye 
was  in  an  embryonic  state,  ran  forward  from 
the  central  artery  of  the  retina  through  the 
hyaloid  canal  to  the  posterior  surface  of  the 

43 


TECHNIQUE    OF    EYE    DISSECTIONS 

lens.  With  the  forceps  pick  up  the  peripheral 
edge  of  the  retina,  and,  by  pulling  gently  up- 
ward, tear  it  away  from  its  apparent  place  of 


Fig.  12 — Picking  up  the  retina  in  order  to  tear  it  away 
from  the  entrance  of  the  optic  nerve. 

attachment  to  the  "entrance"  of  the  optic 
nerve.  (Fig.  12.)  When  this  has  been  done, 
there  will  be  seen  some  threads  protruding 

44 


TECHNIQUE    OF    EYE    DISSECTIONS 

from  the  optic  nerve.  Filling  the  half  with 
water  will  tend  to  separate  these  strands, 
which  are  optic-nerve  elements. 

After   the   removal   of   the   retina,   the   iri- 
descence   of    the    choroid    (tapetum   lucidum) 


Fig.  13 — The  lighter  area  is  the 

field  of  iridescence  of 

the  choroid. 

(Fig.  13)  may  be  examined  with  a,  hand  lens, 
or,  after  its,  removal,  a  piece  may  be  cut 
and  placed  under  a  microscope.  This  irides- 
cence is,  of  course,  not  present  in  the  human 

45 


TECHNIQUE    OF    EYE    DISSECTIONS 

eye.      ("Physiology  of  the   Senses,"   McKen- 
drick  &  Snodgrass,  page  101.) 

After  the  choroid  is  removed,  which  is  ac- 
complished in  the  same  manner  that  the  retina 
is  removed,  the  inner  side  of  the  sclerotic  is 


Fig.  14 — Excavated  posterior  half  of 
the  sclerotic. 

laid  bare  to  view.  The  brownish  color  is 
mostly  due  to  the  presence  of  a  small  amount 
of  pigment  in  the  cells  of  one  of  the  inner  lay- 
ers, it  is  also  due,  to  a  slight  extent,  to  the 
staining  influence  of  the  perichoroidal  fluid. 
(Fig.  14.) 

46 


TECHNIQUE    OF    EYE    DISSECTIONS 

THE   OPTIC   NEKVE 

The  excavated  posterior  half  may  be  used 
now  to  show  and  .to  study  the  construction  of 
the  optic  nerve.  In  cutting  the  optic  nerve 
away  from  the  sclerotic  leave  at  least  5  mm.  of 


Fig.  15 — Enlarged  to  show  the  entrance  of  the  optic 
nerve.     (Page  48.) 

the  sclerotic  attached.  It  will  make  handling 
easier.  With  the  thumb  and  forefinger  of  the 
left  hand  hold  the  nerve  in  such  a  way  on  the 
table  that  it  will  be  straightened  out  length- 
wise, and  then,  using  the  scalpel  or  a  safety- 

47 


TECHNIQUE    OF    EYE    DISSECTIONS 

i  • 

razor  blade,  the  latter  being  preferable,  cut  the 
nerve  in  two  longitudinally.  (Fig.  15.)  The 
cutting  must  be  done  with  one  movement, 
otherwise  the  nerve  will  be  hacked,  and  will 
not  make  a  good  specimen.  This  specimen 


Fig.  16 — Showing  ciliary  processes 
and  crystalline  lens. 

will  show  the  way  the  nerve  fibers  are  ar- 
ranged. A  cross  section  should  be  cut  from 
the  optic  nerve  of  another  eye,  and  then  the 
two  sections  should  be  compared.  The  cross 
section  will  show  the  sheath  of  the  nerve  a 

48 


TECHNIQUE    OF    EYE    DISSECTIONS 

little  better  than  will  the  longitudinal  section. 
In  cutting  the  longitudinal  section,  one  is 
sometimes  so  fortunate  as  to  cut  through  the 
central  blood  vessels  of  the  retina,  These  ves- 
sels will  show  up  then  as  a  rather  thin  dark 
streak  about  5  or  6  mm.  long. 

THE    ANTERIOR    HALF 

The  anterior  half  will  show  the  lens  in  situ, 
the  ciliary  processes,  the  posterior  aspects  of 
the  iris  and  the  lens,  the  corona  ciliaris,  the 
orbicularis  ciliaris,  and  the  ora  serrata,  (Fig. 
16.)  If  the  eye  has  been  cut  in  two  too  far 
forward  of  its  equator,  the  ora,  serrata  will 
not  be  present.  The  ciliary  processes  and  pos- 
terior aspect  of  the  lens  may  be  seen  to  better 
advantage  when  the  anterior  half  of  the  vit- 
reous is  removed.  This  is  done  with  the  dull- 
pointed  tweezers,  by  c'atching  hold  of  the  vit- 
treous  at  any  part  of  its  free  or  cut  margin,  and 
stripping  it  off  both  the  ciliary  processes  and 
the  lens,  using  a  prying,  pulling  movement  to 
do  so.  (Fig.  17.)  The  two  layers  of  the  pig- 
ment cells,  pars  ciliaris  retinae,  which  cover 

49 


TECHNIQUE    OF    EYE    DISSECTIONS 

the  inner  surface  of  the  processes,  may  be  re- 
moved by  picking  them  away  carefully  with 
the  tweezers.  The  processes  then  will  be  seen 
to  be  a  whitish  color.  The  pupillary  edge 


Fig.  17 — Anterior  half,  showing  how  to  pull  off  vitreous. 
(Page  49.) 

of  the  iris  rests  upon  the  capsule  of  the  lens, 
but  the  nearer  the  approach  is  to  the  choroidal 
edge  the  farther  the  iris  is  from  the  lens ;  thus 
are  formed  the  anterior  and  the  posterior 
chambers  of  the  eye.  The  dissection  of  the 
sagittal  section  of  the  eye,  explained  further 

50 


TECHNIQUE    OF    EYE    DISSECTIONS 

on,  will  show  these  two  chambers  in  section. 
One  will  gain  a  much  clearer  conception  of 
their  construction  in  that  section  than  in  the 
"anterior  half "  specimen. 

Now,  remove  the  lens,  using  the  point  of 
the  scalpel  to  cut  through  the  suspensory  liga- 
ment close  to  the  lens.  When  this  has  been 
done  there  will  be  seen  in  the  anterior  cham- 
ber a  thin,  watery  liquid — the  aqueous  humor. 

The  corona  ciliaris  and  orbicularis  ciliaris 
may  be  better  seen  and  studied  if  viewed 
through  a  hand  lens. 

THE  IRIS 

To  see  the  iris,  take  hold  of  the  cut  edge  of 
the  dhoroid,  and,  gently  pulling,  separate  it 
from  its  attachment  to  the  corneo-scleral  junc- 
tion. The  white  ring  on  the  anterior  surface 
of  this  part  of  the  second  coat  of  the  eye  is 
the  ciliary  ring.  With  a  scissors,  cut  around 
this  ciliary  ring  at  its  outer  edge.  This  speci- 
men will  show  the  anterior  surface  of  the  iris, 
and  on  the  posterior  side  it  will  show  the  close 
relationship  between  the  iris  and  the  ciliary 

51 


TECHNIQUE    OF    EYE    DISSECTIONS 

processes.     A  hand  lens  will  help  greatly  to 
bring  -out  the  very  interesting  fine  points. 

THE  COKNEA 

After  the.  anterior  portion  has  had  every- 
thing removed  from  it  there  will  be  left 
nothing  but  the  first  coat  or  tunic  of  the  eye 
—the  anterior  portion  of  the  sclerotic  and 
the  cornea,  The  way  the  cornea  seems  to  fit 
into  the  sclerotic  is  not  quite  as  one  is  led  to 
believe  when  told  that  it  fits  into  the  sclerotic 
much  the  same  way  in  which  a  watch  crystal 
fits  into  a  watch.*  Holding  this  part  of  the 
eye  up  to  a  strong  light  one  will  see  that  the 
sclerotic  seems  to  overlap  the  cornea  in  the 
vertical  axis. 

By  using  the  tweezers  the  cornea  may  be  split. 
Nothing  in  the  way  of  locating  its  layers  can 
be  recognized,  however,  unless  a  section  is 
made  for  microscopic  examination.  The  epi- 
thelial may  be  scraped  off  when  the  cornea  is 
a  trifle  dry.  This  is  the  ocular  epithelium  re- 
duced to  a  layer  of  flattened  cells. 


* ' '  Anatomy    and     Physiology     of     the     Eye, ' '     Brown     & 
Zoethout. 

52 


TECHNIQUE    OF    EYE    DISSECTIONS 

THE    CKYSTALLINE   LENS 

If  the  preceding  dissections  have  been  done, 
the  crystalline  lens  will  already  have  received 
some  notice.  To  study  the  lens  properly  one 
should  use  an  eye  that  has  not  been  hardened 
and  also  an  eye  or  the  lens  of  an  eye  that  has 
been  in  a  5  per  cent,  solution  of  formaldehyde 
for  about  two  weeks. 

The  lens  in  the  unhardened  eye  will  prove 
too  friable  to  permit  much  handling.  The  dis- 
section should  be  made,  however,  in  order  to 
give  opportunity  to  notice  the  crystalline  clear- 
ness of  the  lens  substance,  its  great  magnify- 
ing power,  its  attachments,  its  capsule,  etc. 
For  this  purpose  it  is  necessary  to  proceed 
only  as  in  the  dissection  for  the  "hyaloid  mem- 
brane, etc/'  That  is,  use  an  eye  that  has  been 
kept  in  a  cool  place  for  several  days,  and  then 
open  it,  and  remove  hyaloid,  vitreous,  and  lens 
intact,  as  in  the  first  dissection  taken  up  in 
this  book.  To  examine  the  specimen  in  de- 
tail, turn  it  so  the  lens  will  be  uppermost. 
(Fig.  18.) 

To  remove  the  lens  it  is  necessary  to  sepa- 
53 


TECHNIQUE    OF    EYE    DISSECTIONS 

rate  the  suspensory  ligament,  using  for  this 
purpose  the  small-pointed  scissors.  The  cap- 
sule may  be  removed  by  picking  it  up  on  the 
periphery  of  the  lens,  and  stripping  it  off.  It 
will  peel  off  about  the  same  way  that  the  outer 
skin  of  a  bean  or  pea  does. 


Fig.  18 — Enlarged  to  show  the  processus  zonuloe.     (Page  53.) 

The  tri-radiate  lines  on  the  posterior  and 
the  anterior  surfaces  of  the  lens  will  not  be 
as  clearly  discernible  as  in  the  lens  coming 
from  the  hardened  eye.  Close  inspection  and 
the  use  of  a  hand  lens  will  help  bring  them 
out  more  clearly. 

Now,  with  the  point  of  the  scalpel  try  to 
separate  the  outer  layers  (cortex)  from  the 

54 


TECHNIQUE    OF    EYE    DISSECTIONS 

harder  inner  layers  (nucleus).  This  will 
not  prove  very  successful  but  is  suggested  for 
the  purpose  of  comparison  when  the  same 
thing  is  done  to  the  hardened  lens. 

It  will  be  found  that  the  lens  after  having 
been  in  the  formaldehyde  solution  is  no  longer 
crystal  like,  but  more  or  less  translucent. 
When  viewed  from  either  the  anterior  side  or 
the  posterior  side,  the  tri-radiate  lines  on  each 
surface  will  be  seen  to  begin  at  the  poles  of 
the  lens  and  radiate  outward  toward  the  lens 
equator.  Holding  the  lens  up  to  a  strong 
light  will  show  that  though  the  lines  on  either 
surface  form  angles  of  120  degrees,  the  angles 
formed  by  the  lines  on  one  side  with  the  lines 
on  the  other  side  are  60  degrees.  On  the  an- 
terior surface  of  the  lens  the  vertical  line  ex- 
tends upward  from  the  pole;  on  the  posterior 
surface  downward  from  the  pole. 

To  study  the  laminated  structure  of  the  lens, 
it  is  best  to  boil  the  lens.  The  best  way  to  do 
that  is  to  drop  the  lens  from  either  a  hardened 
or  unhardened  eye  into  boiling  water.  Let  it 
boil  in  the  water  for  about  two  and  a  half  to 

55 


TECHNIQUE    OF    EYE    DISSECTIONS 

three  minutes.  Longer  than  that  time  will 
cause  the  lens  to  be  put  out  of  shape,  and  make 
it  so  fragile  that  it  can  no  longer  be  handled 
without  having  it  fall  apart.  If  the  lens  comes 
from  an  unhardened  eye  it  might  be  best  to 
boil  it  not  more  than  about  two  minutes. 


Fig.  19 — Showing  the  way  the  onion-like  layers  of 
the  lens  may  be  peeled  off. 

Insert  the  point  of  the  scalpel  carefully  at 
one  of  the  poles,  and  lift  gently  in  the  direc- 
tion of  one  of  the  radiating  lines.  This  will 
tend  to  raise  one  of  the  concentric  layers, 
which  can  be  easily  peeled  off.  Eepeat  this  in 
the  direction  of  the  other  two  radiating  lines. 
Examining,  with  a  hand  lens,  the  exposed  sur- 

56 


TECHNIQUE    OF    EYE    DISSECTIONS 

faces  and  the  layers,  as  they  are  taken  off, 
will  show  the  arrangement  of  the  lens  fibres, 
and  will  also  show  plainly  their  directions. 
(Fig.  19.)  To  get  another  view  of  the  onion- 
like  layers  of  the  lens,  cut  through  it  with  a 


Fig.  20 — Section  through  lens  show- 
ing its  concentric  layers. 

safety-razor  blade,  either  longitudinally  or 
equatorially.  (Fig.  20.)  The  better  way  is  to 
have  enough  lenses  to  make  one  of  each  kind. 
Never  try  to  work  with  only  one  piece  of 
material.  If  the  lens  is  first  stained  with  chro- 
mic acid  the  layers  may  be  seen  better,  or,  a 
simpler  way  is  to  drop  the  lens,  before  cutting 
it  in  two,  into  a,  carmine  solution;  red  ink 
slightly  diluted,  will  do. 
A  lens  that  has  been  boiled  and  partly  dis- 
57 


TECHNIQUE    OF    EYE    DISSECTIONS 

sected  may  be  placed  in  a,  5  per  cent,  formalde- 
hyde solution,  and  kept  indefinitely.  The  lens 
fibres,  concentric  layers,  and  lens  laminae  in 
such  a  specimen  will  always  be  interesting. 

A  lens  that  has  lost  its  transparency  be- 
cause of  hardening  in  formaldehyde  or  boiling 
may  be  made  clear  and  nearly  transparent 
again  in  the  following  way:  First:  Place  the 
lens  in  a  50  per  cent,  alcohol  for  several  hours. 
Second :  Remove  the  lens,  and  let  it  drain  on  a 
piece  of  blotting-paper;  then  place  it  in  a  75 
per  cent,  alcohol.  Third:  Eemove  the  lens,  as 
before,  then  place  it  in  an  85  per  cent,  alco- 
hol. The  lens  may  be  left  in  this  alcohol  from 
ten  to  twelve  hours,  after  which  length  of  time 
it  should  be  removed  and  drained.  Fourth: 
Place  the  lens  in  an  absolute  alcohol,  and  leave 
it  there  for  ten  or  twelve  hours.  Several  hours 
longer  will  not  injure  the  lens,  nor  interfere 
with  the  success  of  the  work.  Fifth:  Remove 
the  lens  from  the  absolute  alcohol.  Place  it 
upon  a  piece  of  blotting-paper,  moving  it  to 
another  place  on  the  blotting-paper  whenever 
the  paper  around  the  lens  seems  to  have  taken 

58 


TECHNIQUE    OF    EYE    DISSECTIONS 

up  as  much  moisture  as  it  can  hold.  Be  sure 
that  the  lens  has  given  up  nearly  all,  if  not  all, 
moisture.  "Kunning  through  the  alcohols/' 
as  this  process  is  called,  is  for  the  purpose  of 
dehydrating  the  tissue.  It  will  be  on  the  side 
of  safety  to  let  the  lens  lie  exposed  on  the  blot- 
ting-paper for  an  hour.  Sometimes,  if  the 
capsule  has  not  been  removed,  a  small  quan- 
tity of  alcohol  will  remain  between  the  lens 
and  the  inner  surface  of  the  capsule.  This 
must  be  removed.  It  may  be  done  by  either 
puncturing  the  capsule  with  a  pin  or  needle, 
and  squeezing  out  the  fluid,  or  by  removing  the 
capsule  entirely.  The  latter  is  preferable. 

Now  drop  the  lens  into  xylol.  Benzine  will 
answer,  though  it  will  not  produce  quite  so 
clear  a  lens  as  the  xylol  does.  At  the  end  of 
24  or  36  hours  the  softer  cortex  will  show  quite 
clear,  while  the  harder  nucleus  will  be  still 
cloudy.  At  the  end  of  a  week  the  whole  lens, 
if  it  is  a  small  one^-pig,  calf,  sheep — will  have 
become  quite  clear  and  transparent;  if  from  a 
beef  eye  it  will  take  longer.  It  sometimes  takes 
nearly  two  weeks.  In  the  case  of  a  boiled  lens 

59 


TECHNIQUE    OF    EYE    DISSECTIONS 

it  will  take  much  longer  to  clear;  it  may  take 
a  month. 

Cedar  oil  may  also  be  used  for  the  purpose 
of  clarifying  or  "clearing"  the  lens.  Harden 
in  the  usual  way,  run  through  the  alcohols,  and 


ABC  D 

Fig.  21. 

A.  Lens  hardened  in  formaldehyde. 

B.  Lens  hardened  in  formaldehyde,  run  through  the  alcohols, 

and  cleared  in  xylol. 

C.  Lens  hardened  in  formaldehyde,  run  through  the  alcohols, 

and  cleared  in  cedar  oil. 

D.  Boiled  lens. 

then  place  in  cedar  oil.  The  oil,  however,  will 
stain  the  lens  a  yellowish  brown,  and  the  lens 
will  not  be  as  transparent  and  clear  as  when 
xylol  is  used. 

The  longer  a  lens  is  left  in  either  of  these 
two  clarifying  fluids  the  harder  and  smaller  it 
will  become.  At  the  end  of  a  month  or  six 

60 


TECHNIQUE    OF    EYE    DISSECTIONS 

weeks  the  lens  will  have  become  so  hard  that 
it  can  no  longer  be  cut  through  with  a  knife. 
If  it  is  desired  to  halve  it,  a  scroll  saw  will 
be  found  to  be  the  best  thing  to  use  for  this 
purpose.  (Fig.  21.) 


til 


THE   CHOEOID 

SELECT  an  eye  that  has  had  a  long  part  of 
the  optic  nerve  left  on  it  and  place  it  into  a 
5  per  cent,  solution  of  formaldehyde.  Leave 
it  in  that  solution  for  from,  two  to  three 
weeks.  That  period  of  time  in  the  fluid  will 
be  sufficient  to  permit  the  choroid  to  become 
sufficiently  toughened  and  hardened.  Leaving 
it  in  the  solution  longer  than  that  length  of 
time  will  not  injure  the  eye  in  any  way. 

After  having  removed  the  eye  from  the 
formaldehyde,  wash  it  for  a  few  moments  in 
running  water.  This  will  remove  the  preserv- 
ing and  hardening  fluid  from  the  surface,  and 
will  save  the  hands  a  little  from  the  effects 
of  the  fluid.  Next  remove  all  the  muscles 
and  fatty  tissues  from  the  sclerotic.  After 
that  has  been  done,  puncture  the  cornea  with 
the  pointed  jaw  of  the  scissors  about  2  mm. 
from  the  corneo-scleral  junction.  (Fig.  22.) 
Then  proceed  to  cut  the  cornea  away,  being 

62 


TECHNIQUE    OF    EYE    DISSECTIONS 

careful  not  to  lacerate  the  choroid  or  the 
iris.  (Fig.  23.)  The  escaping  aqueous  humor 
will  flow  over  the  eye  and  make  it  very  slip- 
pery, and,  therefore,  difficult  to  hold.  Dip  the 


I! f 


Fig.  22 — Showing  how  to  puncture  the  cornea. 
(Page  62.) 

eye  in  water,  wash  it,  and  then  take  it  out  and 
thoroughly  dry  it  with  a  cloth.  This  procedure 
is  absolutely  necessary,  and,  if  omitted,  will 
surely  result  in  the  dropping  of  the  eye  about 

63 


TECHNIQUE    OF    EYE    DISSECTIONS 

the  time  the  work  on  the  specimen  is  nearly 
finished.  Insert  the  scalpel  between  the 
peripheral  edge  of  the  exposed  iris  and  what 


Fig.  23 — Eemoving  the  cornea.     (Page  63.) 

is  left  of  the  cornea,  With  the  back  edge  of 
the  scalpel,  gently  loosen  the  choroid  from 
the  inner  side  of  the  corneo-scleral  junction  to 

64 


TECHNIQUE    OF    EYE    DISSECTIONS 

which  part  it  is  not  securely  attached.  (Fig. 
24.)  This  requires  only  ordinary  care,  and  but 
little  skill  other  than  that  necessary  to  always 


Fig.  24 — Showing  method  of  inserting  the  scalpel  to  separate 
the  choroid  from  the  sclerotic. 

keep  the  scalpel  close  to  the  inner  surface  of  the 
sclerotic.  When  the  choroid-iris  edge  has 
been  detached  from  the  inner  side  of  the  cor- 

65 


TECHNIQUE    OF    EYE    DISSECTIONS 

iieo-scleral  junction,  the  weight  of  the  con- 
tents of  the  second  tunic  will  cause  it  to  sag 
and  give  opportunity  to  easily  separate,  with 
the  back  edge  of  the  scalpel,  the  choroid  from 
the  sclerotic  for  about  a  distance  of  from  8 
to  10  mm. 

It  has  been  the  method  in  the  past  to  force 
water  through  a  blowpipe  between  the  scle- 
rotic and  the  choroid,  in  order  to  separate  the 
attachments.  It  has  also  been  the  method  to 
work  under  water  when  wishing  to  expose  or 
isolate  either  the  choroid  or  the  retina,  It 
is  unnecessary  to  do  either  of  these  two  things. 

When  the  sclerotic  has  been  loosened  from 
the  choroid  for  about  10  him.  back  from  its 
cut  edge  around  the  eye,  carefully  cut  the 
loosened  part  away.  (Fig.  25.)  Then  loosen 
the  choroid  as  far  back  as  to  within  1  cm.  of 
the  optic  nerve.  Cut  the  separated  sclerotic 
away.  It  will  be  well  to  state  here  that  during 
this  dissection  the  specimen  should  not  be 
lifted  from  the  table.  Keep  the  eye  resting 
on  the  table  all  the  time,  and  never  lift  it  by 
holding  it  suspended  from  the  optic  nerve. 

66 


TECHNIQUE    OF    EYE    DISSECTIONS 

Loosening  the  choroid  from  the  sclerotic  up 
to  this  point  is  a  very  easy  matter;  ordinary 
precaution  is  all  that  is  necessary  to  prevent 


Fig.  25— Cutting  away  the  sclerotic  after  it  has  been  loosened 
from  the  choroid,  as  shown  in  Fig.  24. 

puncturing  the  choroid  with  the  scalpel,  just 
be  sure  to  remember  to  keep  the  point  of  the 
scalpel  close  to  the  sclerotic. 

67 


TECHNIQUE    OF    EYE    DISSECTIONS 

To  remove  the  remaining  part  of  the  first 
coat  is  a  little  more  difficult,  and  needs  a  little 
more  care.  Hold  the  optic  nerve  in  the  left 
hand,  and  pull  it  so  that  the  sclerotic  will  pull 


Fig.  26. — Showing  how  to  scrape  the  choroid  free  from  the 
sclerotic  near  the  optic  nerve. 

away  from  the  choroid.  Then,  using  the  cut- 
ting edge  of  the  scalpel,  scrape  the  choroid 
loose  from  the  sclerotic  close  up  to  the  en- 
trance of  the  optic  nerve.  (Fig.  26.)  Do  not 

68 


TECHNIQUE    OF    EYE    DISSECTIONS 

separate    the    opic    nerve    from    the    choroid. 
Cut  away  the  remainder  of  the  sclerotic  close 


Fig.  27 — Showing  the  choroid,  the  optic 

nerve  still  attached,  the  ciliary  ring, 

and  the  ciliary  nerves. 

up  to  the  optic  nerve  and  the  choroid  will  be 
free.     (Fig.  27.) 

To  get  a  perfect  specimen  and  completely 
isolated  choroid,  it  must  be  emptied  of  its  con- 
tents. Insert  the  scalpel  between  the  lens 

69 


TECHNIQUE    OF    EYE    DISSECTIONS 

and  the  iris,  force  it  on  through,  and  in  such 
a  manner  as  to  keep  the  scalpel  close  to  the 
ciliary  processes.  (Fig.  28.)  Cut  the  vitreous 
around  the  processes.  Push  the  scalpel  fur- 
ther into  the  vitreous,  and  cut  out  the  central 


Fig.  28 — Showing  method  of  inserting  scalpel  in  order  to  loosen 
the  lens  and  cut  through  the  vitreous. 

part  of  it,  just  as  one  would  cut  out  the  core 
of  an  apple.  (Fig.  29.)  Eemove  the  scalpel, 
pick  out  the  lens  and  the  cut  centre  of  the 
vitreous  with  the  broad-point  tweezers,  holding 
the  choroid  a  trifle  suspended  by  the  optic- 
nerve.  The  remaining  part  of  the  vitreous  may 
be  broken  down  by  cutting  with  the  scalpel,  and 

70 


TECHNIQUE    OF    EYE    DISSECTIONS 

by  squeezing  and  crushing  with  the  fingers  of 
both  hands.  (Fig.  30.)  The  choroid  will  be 
tough  enough  to  stand  this  treatment  provided 


Fig.  29 — Taking  out  the  lens  and  "core"  of  the  vitreous. 

the  pupil  is  left  clear  and  open  to  prevent 
inter-choroidal  pressure.  After  the  vitreous 
has  been  removed  the  choroid  will  be  left  in  a 
greatly  collapsed  condition.  Dropping  it  into 

71 


TECHNIQUE    OF    EYE    DISSECTIONS 

water  and  letting  it  fill  up  will  make  it  resume 
its  original  shape  immediately.  The  retina 
does  not  always  come  out  with  the  vitreous. 


Fig.  30 — Showing  how  to  squeeze  out  the  remaining  part  of  the 
vitreous  (A)  from  the  choroid,     (Page  71.) 

In  such  a  case,  the  tweezers  may  be  used  to 
pick  out  the  retina  when  the  choroid  is  in  a 
collapsed  condition. 

72 


TECHNIQUE    OF    EYE    DISSECTIONS 

This  specimen  will  show  the  vena  vorticosa, 
the  ciliary  nerves,  and  their  way  of  ramifying, 
and  the  long  ciliary  arteries,  which  run  oppo- 
site each  other  and  which  may  be  recognized 
by  their  rather  colorless,  tubular  appearance. 
The  evacuated  choroid  makes1  an  excellent 
specimen  and  one  easily  examined.  Place  it 
in  a  3  per  cent,  solution  of  formaldehyde,  and 
then  examine  with  a  skiascope,  an  ophthalmo- 
scope, or  by  "oblique  illumination. " 

This  dissection  is  wholly  original,  and  may 
be  done  in  about  five  minutes.  The  old  tech- 
nique for  doing  it  required  at  least  an  hour 
of  time  with  the  possibility  of  procuring  one 
perfect  specimen  in  every  six  or  seven.  The 
technique  as  given  here  will  make  it  possible 
to  do  the  work  in  not  longer  than  five  or  six 
minutes  for  the  beginner,  and  about  four  min- 
utes for  the  expert. 


73 


THE  EETINA 

ISOLATING  the  retina  from  the  other  tissues 
requires  considerable  patience  and  dexterity. 
When  the  retina  has  been  removed  and  placed 
in  a  special  receptacle,  it  will  be  found 
that  the  specimen  is  well  worth  the  little 
amount  of  time  spent  in  making  it.  Previous 
techniques,  even  the  writer's  own,  sometimes 
took  nearly  two  hours  to  do,  and  rarely  was 
the  retina  isolated  without  puncturing  or  tear- 
ing it;  perfect  specimens  were  almost  impossi- 
ble. The  following  method  will  assure  one  of 
success  in  nearly  every  instance.  Failures  are 
almost  impossible.  Punctures,  perforations, 
tears,  etc.,  are  rare.  The  beginner  should 
isolate  the  retina  in  about  six  to  seven  min- 
utes; the  expert  in  about  four  and  a  half  to 
five  minutes. 

Select  an  eye  with  a  long  optic  nerve,  and 
prepare  it  for  this  dissection  by  placing  it  in 
a  10  per  cent,  solution  of  formaldehyde  for 

74 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  31 — Cutting  through  the  iris.     (Page  77.) 

about  ten  to  fourteen  days,  but  no  longer.  If 
it  is  left  in  the  hardening  fluid  longer  than  that 
length  of  time,  it  will  interfere  with  the  easy 
removal  of  the  vitreous. 

75 


TECHNIQUE    OF    EYE    DISSECTIONS 

The  first  part  of  this  dissection  is  the  same 
as  the  beginning  of  the  dissection  for  the 
isolation  of  the  choroid.  Eemove  all  the  out- 


Fig.  32 — Showing  how  to  cut  around  the  ciliary  ring. 
(Page  77.) 

side  tissues  first,  and  then  the  cornea,  and 
about  10  mm.  of  the  sclerotic,  as  described  in 
the  preceding  dissection.  (See  Figs.  22,  23, 
24,;  and  2&.)  That  will  lay  bare  the  iris  and 
a  few  millimetres  of  the  choroid. 

76 


TECHNIQUE    OF    EYE    DISSECTIONS 

After  that  has  been  done,  turn  the  eye  so 
the  iris  will  be  uppermost.  With  the  tweezers 
pick  up  the  pupillary  margin  of  the  iris,  and 
with  the  fine-pointed  scissors  cut  through  the 


Fig.  33 — Lens,  iris,  and  part  of  vitreous  removed. 
(Page  78.) 

iris  and  the  ciliary  processes  (Fig.  31) ;  sep- 
arate both  from  the  choroid  by  cutting  close 
to  the  posterior  edge  of  the  processes.  (Fig. 
32.)  In  doing  that,  cut  partly  through  the 
vitreous  also,  but  be  careful  not  to  injure  the 
peripheral  edge  of  the  retina — ora  serrata, 
After  the  iris  has  been  separated  from  the 
choroid,  cut  completely  through  the  vitreous 

77 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  34 — Showing  how  to  force  glass  blowpipe  (A) 
into  vitreous  (B).     (Page  80.) 

in    such    a   way    that    the    lens    will    also    be 
removed  with  the  iris.      (Fig.  33.) 

Holding  the  eye  suspended  by  its  optic 
nerve,  force  the  glass  blowpipe  through  the 
vitreous  until  it  all  but  touches  the  posterior 

78 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  35 — Showing  bulging  out  of  vitreous 

caused  by  blowing  air  through 

glass  blowpipe.     (Page  80.) 


79 


TECHNIQUE    OF    EYE    DISSECTIONS 


part  of  the  retina  (Fig.  34)  ;  blow  gently  at 
first,  increasing  the  pressure  until  the  vitreous 
suddenly  bulges  outward.  (Fig.  35.)  If  the 
iris  has  been  cut  away  close  to  the  ora  serrata, 


Fig.  36 — Showing  the  vitreous  (A)  removed. 

the  vitreous  will  not  only  bulge  forward,  but  it 
will  fall  out.  If,  however,  it  does  not  detach 
itself  at  once,  insert  the  scalpel  close  to  the 
choroid  and  with  its  flat  side  press  downward 

80 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  37 — A.  Showing  retina  folded  upon  itself  by  blow- 
ing air  at  it  through  the  glass  blowpipe.     (Page  83.) 

until  a  separation  occurs.  Do  not  let  the 
vitreous  drop  out  too  suddenly,  because  it  may 
tear  the  retina,  Let  the  vitreous  detach  itself 
slowly  by  the  force  of  its  own  weight,  though 
it  will  be  well  to  hold  some  of  its  weight  on  the 
scalpel.  (Fig.  36.) 

81 


TECHNIQUE    OF    EYE    DISSECTIONS 

After  the  vitreous  has  been  removed,  turn 
the  eye  upward,  and  by  blowing  strongly 
through  the  blowpipe  at  the  marginal  edge  of 


m i 


Fig.  38 — A.  Showing  folded  retina  suspended  from  its  attach- 
ment, so  sclerotic  and  choroid  may  be  easily  cut.  away. 
(Page  83.) 

the  retina,  turn  the  retina  upon  itself.  Eepeat 
this  until  the  retina  lies  in  a  small  wrinkled 
lump  at  the  "  bottom "  of  the  posterior  part 

82 


TECHNIQUE    OF    EYE    DISSECTIONS 

of  the  eye.  (Fig.  37.)  Invert  the  eye  (Fig.  38) 
and  cut  away  both  the  choroid  and  the  sclerotic 
close  to  the  optic  nerve.  No  care  need  be 


Fig.  39 — Showing  the  sclerotic  nearly  all  cut  away. 

taken  in  doing   this   until   the    scissors   come 
close  to  the  optic  nerve.     (Fig.  39.) 

After   the    choroid    and   the    sclerotic   have 
been    cut    away,    drop    the    retina    into    some 

83 


TECHNIQUE    OF    EYE    DISSECTIONS 

water,  and  it  will  slowly  unfold  itself  by  "bal- 
looning" out  into  a  perfect  and  beautiful 
specimen.  (Fig.  40.)  But,  if  it  is  desired  to 
study  the  specimen  closely,  it  is  better  to  sus- 
pend it  in  a  jar  or  bottle  made  of  thin  glass, 


Fig.  40 — Isolated  retina,  with  optic  nerve  attached. 

and  containing  a  5  per  cent,  solution  of  formal- 
dehyde. Eemember  that  the  retina  is  a  deli- 
cate membrane  in  any  state;  the  slightest 
rough  handling  may  cause  it  to  be  torn,  or 
otherwise  damaged.  If  the  vessel,  in  which 

84 


TECHNIQUE    OF    EYE    DISSECTIONS 

the  specimen  has  been  placed  and  suspended, 
has  enough  preserving  fluid  to  completely  fill 
it,  and  it  is  firmly  stoppered,  the  whole  thing 
may  be  inverted,  and  turned  in  any  direction, 
even  abruptly,  without  fear  of  damaging  the 
retina,  This  way  of  keeping  the  retina  will 
give  opportunity  to  inspect  and  study  the 
inside  as  well  as  the  outside  of  the  membrane ; 
the  blood-vessels,  and  other  important  parts 
easily  recognized. 


85 


THE  SAGITTAL  OR  VERTICAL  SECTION 
OF  THE  EYE 

PLACE  an  eye  in  a  5  per  cent,  solution  of 
formaldehyde  for  about  two  weeks.  If  the  eye 
is  kept  in  that  solution  longer  than  that  time, 
the  lens  is  apt  to  become  so  hard  that  in  cut- 
ing  it  the  capsule  and  suspensory  ligament 
will  be  torn,  and  the  lens  will  then  become 
detached;  if  for  a  shorter  space  of  time,  the 
lens  and  other  tissues  will  be  so  soft  that  all 
may  be  so  badly  torn  or  lacerated,  that  a  per- 
fect specimen  will  not  be  possible. 

It  sometimes  happens  that  in  keeping  a 
number  of  eyes  together  in  a  vessel  for  the 
purpose  of  hardening  them  in  the  formalde- 
hyde solution,  the  corneas  of  some  will  be 
crushed  in.  For  this  dissection,  select  an  eye 
that  has  the  cornea,  in  perfect  condition. 

Remove  all  the  outside  tissues  with  the 
scissors,  being  particular  to  have  the  region 
immediately  surrounding  the  optic  nerve  per- 

86 


TECHNIQUE    OF    EYE    DISSECTIONS 

fectly  clear  and  clean.     If  the  optic  nerve  is 
longer  than  5  mm.,  cut  it  off  to  that  length. 

To  cut  the  eye  in  two,  use   a  safety- razor 
blade;  never  a  scalpel.   The  latter  is  too  thick, 


Fig.  41 — Showing  the  beginning  of 

the  cutting  of  the  eye  for 

sagittal  sections. 

too  dull,  and  too  clumsy  a  tool.  Begin  by  cut- 
ting through  the  optic  nerve;  dividing  it  as 
nearly  as  possible  into  halves.  (Fig.  41.)  Con- 
tinue cutting  through  the  sclerotic  and  all 
underlying  tissues,  stopping  at  the  corneo- 
scleral  junction,  but  do  not,  during  this  pro- 

87 


TECHNIQUE    OF    EYE    DISSECTIONS 

cedure,  even  touch  the  lens.  After  the  eye 
has  been  thus  partly  separated  into,  as  nearly 
as  possible,  two  equal  parts,  lay  it  down  upon 


Fig.  42 — Showing  method  of  cutting  through  the  crystalline  lens. 

the  cornea,  and,  holding  the  razor  blade  in  the 
forefingers  and  thumbs  of  both  hands,  cut  the 
lens  in  two  by  forcing  the  blade  down  through 
it.  (Fig.  42.)  Partly  open  the  cut  eye  to  allow 
one  jaw  of  the  large  scissors  to  enter,  turn 
the  eye  over  so  the  cornea  will  rest  on  that 

88 


TECHNIQUE    OF    EYE    DISSECTIONS 

jaw,  and  then  cut  through  the  cornea,  (Fig.  43.) 

The  two  specimens  may  be  kept  indefinitely 

by  placing  them  in  a  3  per  cent,  formaldehyde 

solution.     It  will  be  well  to  remove  the  lens 


Fig.  43 — Showing  method  of  cutting  through  the 
cornea  and  completing  the  two  sagittal  sections. 

from  one  of  the  specimens,  because  it  will  give 
better  opportunity  to  see  the  anatomical  rela- 
tionships. Also,  these  specimens  should  be 
mounted,  one  above  the  other,  between  two 
pieces  of  glass,  before  placing  them  in  the 
receptacle  that  is  to  hold  them. 


TECHNIQUE    OF    EYE    DISSECTIONS 

Much  can  be  studied  in  such  specimens. 
Moreover,  they  present  to  view  the  various 
parts  of  the  organ  of  vision  in  such  an  im- 


Fig.  44 — Sagittal  section  enlarged. 

pressive  way,  that  one  does  not  soon  forget 

the  wonderful  appearance  of  the  construction 

of  this,  Nature's  perfect  camera.     (Fig.  44.) 

If  another  eye  is  cut  into  two  parts,  addi- 

90 


TECHNIQUE    OF    EYE    DISSECTIONS 

tional  interesting  specimens  may  be  procured; 
for  instance,  one  showing  the  presence  of  the 
second  coat  only,  the  retina  having  been  torn 
out.  Another  good  specimen  may  be  made  by 
removing  all  of  the  inner  tissues,  and  leaving 
only  the  sclerotic  and  cornea.  This  specimen 
will  show  that  the  first  coat  is  almost  entirely 
a  coat  which  affords  strength  and  protection 
to  the  parts  that  lie  within. 


THE  PAPILLA,  PUNCTA  LACRIMALIA, 
AND  NASAL  DUCT 

THE  only  way  to  dissect  the  lacrimal  appara- 
tus, other  ocular  accessories,  and  the  extrinsic 
muscles,  is  to  procure  the  head  of  some  animal, 
preferably  a  calf's  head,  because  of  its  size. 
Any  butcher  will  supply  one  for  from  forty 
to  sixty  cents.  Have  the  lower  jaw  removed. 
It  will  make  a  less  bulky  piece  of  material  to 
handle. 

Close  to  the  inner  canthus,  on  the  inner  side 
of  each  lid,  will  be  found  a  little  rounded 
eminence — lacrimal  papilla — in  the  centre  of 
which  is  a  small  opening — punctum  lacrimalis. 
Both  may  be  seen  better  on  the  lower  lid,  if 
it  is  pulled  down,  and  on  the  upper  lid,  if  it 
is  pulled  up. 

Be  supplied  with  two  knitting-needles.  Take 
one,  lubricate  its  full  length  with  a  little 
vaseline,  lard,  oil,  or  any  other  lubricant. 
Insert  the  needle  into  the  punctum  of  the 

92 


TECHNIQUE    OF    EYE    DISSECTIONS 

lower  lid,  and  push  it  downward  and  forward, 
liming  to  come  out  in  the  nose  a  short  dis- 
tance from  its  end.  At  first  it  may  be  a  little 


Fig.  45 — Showing  only  a  part  of  a  calf  'a  head  and  the  knitting- 
needles  inserted  in  the  puncta.     (Page  94.) 

difficult  to  get  the  needle  started;  if  so,  just 
wiggle  the  needle,  pushing  it  at  the  same  time 
as  directed,  until  the  nasal  duct  is  found.  Do 
not  remove  the  needle.  To  insert  the  other 

93 


TECHNIQUE    OF    EYE    DISSECTIONS 

needle  into  the  punctum  of  the  upper  lid  is 
rather  difficult;  for  that  reason  the  punctum 
of  the  lower  lid  was  chosen  first.  Grease  the 


Fig.  46. 

needle,  as  was  done  to  the  first  one,  and,  with 
a  little  patience  and  careful  manipulation,  the 
canal  opening  and  its  course  will  soon  be 
found.  The  needle  may  then  be  pushed 
through  until  it  meets  the  first  one.  (Fig.  45.) 

94 


TECHNIQUE    OF    EYE    DISSECTIONS 

From  the  puncta  lacrimalia  to  the  place  of 
meeting  of  the  two  needles,  marks  the  course 
of  the  two  canaliculi  and  their  junction  before 
they  merge  and  form  the  nasal  duct.  Leave 
the  needles  where  they  are,  and  begin  cutting 
away  the  skin.  The  needles  will  then  mark 
the  course  of  each  canal  and  the  duct  very 
plainly.  With  the  small  scissors  the  canals 
and  the  duct  may  be  loosened  from  the  sur- 
rounding tissues.  Or,  the  scalpel  may  be  used 
to  lay  open  the  canals,  cutting  along  over  the 
top  of  the  needles.  (Fig.  46.) 

The  cilia,  palpebrae,  palpebral  conjunctiva, 
ocular  conjunctiva,  and  other  superficial  ocular 
accessories  may  be  examined  without  dissec- 
tion. 


95 


TECHNIQUE    OF    EYE    DISSECTIONS 


MEIBOMIAN    GLANDS   AND   DUCTS 

AN  examination  of  the  eyelids  will  show  the 
openings  of  the  ducts  of  the  meibomian  glands 
a  short  distance  back  of  the  cilia.  Very  fine 
pins  or  needles  that  have  been  greased  may 
be  easily  inserted  for  a  short  distance  into  the 
ducts,  and  then  a  dissection  made  along  the 
course  of  the  duct  as  outlined  by  the  presence 
of  the  inserted  pins  or  needles.  Another  way 
to  see  the  glands  is  to  slice  through  the  ducts, 
with  the  scalpel  or  safety-razor  blade,  the 
entire  width  of  either  eyelid.  This  will  sepa- 
rate the  glands  into  two  parts  and  show  their 
length,  breadth  and  structure. 


96 


ENUCLEATION  OF  THE  ORBITAL 
CONTENTS 

THE  eyes  one  procures  from  a  butcher  or  a 
slaughter  house  will  always  have  the  extrinsic 
tissues  so  badly  cut  and  torn  that  identification 
of  the  various  parts  and  their  relations  is 
impossible.  Therefore,  it  is  best  to  supply 
one's  self  with  the  head  of  an  animal,  such  as 
a  sheep  or  a  calf,  and  dissect  an  eye  with  all 
its  extrinsic  tissues  intact.  For  this  dissec- 
tion, a  hammer  and  a,  chisel  are  necessary  in 
addition  to  the  tools  needed  for  doing  the 
previous  dissections. 

Using  the  left  orbit,  begin  the  dissection  by 
making  an  incision  directly  over  the  supra- 
orbital  ridge,  extending  from  over  the  inner 
to  the  outer  canthus.  At  the  middle  of  that  line, 
make  an  incision,  and  cut  at  right  angles  up- 
ward to  the  top  of  the  head.  Next  make  a  cut 
below  the  eye,  extending  from  the  outer  to 
the  inner  canthus.  (Fig.  47.)  Loosen  the  skin 

97 


o 

bjo 

£ 


98 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  48 — Part  of  calf 's  head,  showing  the  first  cut  to  be  made 
in  the  bones  of  the  orbit.     (Page  102.) 

from  the  bone  with  the  scalpel,  and  lay  bare 
the  skull  immediately  over  the  orbit.  Fold  the 
flaps  of  the  skin  back  and  fasten  them  down 
to  the  skull  with  pins  or  tacks  so  they  will  not 
interfere  with  the  work. 

Using    the    hammer    and    the    chisel,    cut 
99 


TECHNIQUE    OF    EYE    DISSECTIONS 

through  the  roof  of  the  orbit  at  the  middle  of 
the  supra-orbital  ridge,  and  continue  upward 
for  about  two  and  one-half  inches.  Do  not 
strike  hard  blows,  or  the  chisel  may  be  driven 


Fig.  49 — Showing  all  the  cuts  to  be  made  through  the  bones 
of  the  orbit.     (Page  102.) 

through  the  underlying  tissues.  Listen  for 
the  peculiar  sound  that  is  heard  when  the 
bone  has  been  completely  penetrated;  then  re- 
move the  chisel.  Continue  until  the  full  dis- 
tance of  two  and  one-half  inches  of  bone  has 

100 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  50 — Showing  how  to  pry  the  cut  bone  loose.     (Page  102.) 


101 


TECHNIQUE    OF    EYE    DISSECTIONS 

been  separated.  (Fig.  48.)  Now,  begin  at  the 
upper  end,  and  cut  through  the  bone  downward 
to  the  right  for  about  two  inches  toward  the 


Fig.  51 — ' '  In  removing  orbital  contents  dissect  close 
to  the  bone." 

outer  canthus.  A  similar  line  should  be  cut 
on  the  right  of  the  centre  line  toward  the  inner 
canthus.  This  will  mark  out  two  irregular, 
triangular-shaped  pieces  of  bone.  (Fig.  49.) 
Remove  the  piece  on  the  right-hand  side  by 
prying  it  off.  (Fig.  50.)  The  left-hand  piece 
should  be  pried  loose  and  then  carefully  cut 
away  with  the  scalpel,  so  that  the  pulley  through 

102 


TECHNIQUE    OF    EYE    DISSECTIONS 

which  the  superior  oblique  muscle  runs  its 
tendon,  will  not  be  injured.  In  removing  the 
orbital  contents,  dissect  close  to  the  bone  (Fig. 
51),  so  that  the  periosteum  will  also  be  re- 
moved, and  form  a  sort  of  sac  or  capsule  in 


Fig.  52 — Showing  excavated  orbit.     (Page  105.) 

which  will  be  contained  the  eye  with  all  its 
extrinsic  tissues.  If  difficulty  is  experienced 
in  getting  at  the  posterior  parts  of  the  orbit, 
it  will  be  best  to  cut  away  as  much  more  of 
the  obstructing  bone  as  is  necessary.  In  this 
way  the  "capsule"  containing  the  eye,  its  six 

103 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  53 — Anterior  view  of  the  enucleated  eye. 


Fig.  54 — Showing  the  enucleated  eye,  its  muscles,  and  its 
accessories,  all  in  situ. 

104 


TECHNIQUE    OF    EYE    DISSECTIONS 

muscles,  the  lacrimal  gland,  and  both  eyelids, 
all  in  situ,  will  be  removed.  (Fig.  54.)  As  the 
orbital  entrance  of  the  optic  nerve  is  neared, 
care  must  be  exercised  not  to  cut  into  this 
"capsule,"  or  sever  any  of  the  muscles.  (Fig. 
52  shows  the  excavated  orbit.  Fig.  53  shows 
an  anterior  view  of  the  enucleated  eye.  Fig.  54 
is  a  side  view  of  the  enucleated  eye.) 


105 


OPHTHALMOSCOPIC  EXAMINATION 

BY  practising  on  an  enucleated  eye,  one  may 
gain  considerable  ability  in  the  use  of  the 
ophthalmoscope,  and  also  learn  to  recognize 
the  blood-vessels  and  other  important  parts  of 
the  retina.  To'do  this,  the  eye  to  be  examined 
must  be  very  fresh,  for  only  in  this  condition 
will  the  cornea  and  lens  be  sufficiently  clear  to 
permit  rays  of  light  to  enter  the  inside  of  the 
eye. 

However,  since  the  pupil  is  oblong  in  shape, 
and  often  only  a  narrow  slit — but  several 
millimetres  in  diameter — the  field  presented 

for  observation  is  a  rather  limited  one.    To 

5- 

increase  the  pupillary  aperture,  take  a  pin, 
and  force  the  point  through  the  cornea  about 
three  or  four  millimetres  from  the  corneo- 
scleral  junction,  and  at  right  angles  to  the 
direction  of  the  parallel  edges  of  the  pupil. 
After  the  pin  has  been  pushed  through  until 
it  has  reached  to  within  a  short  distance  (one 

106 


TECHNIQUE    OF    EYE    DISSECTIONS 

millimetre)  of  the  edge  of  the  iris,  carefully 
pick  up  the  iris  by  raising  the  pin  into  a 
position  perpendicular  to  the  cornea,  and  force 


Fig.  55 — Showing  one  pin  before  the  iris  has  been  picked  up 

and  pulled  back,  and  three  pins  after  the  iris  has 

been  picked  up  and  pulled  back. 

the  pin  further  down  into  the  eye.  The  pupil 
will  have  been  enlarged  on  one  side.  Do  the 
same  thing  on  the  opposite  side,  and  at  each 
extremity  of  the  pupil.  (Fig.  55.) 

107 


TECHNIQUE    OF    EYE    DISSECTIONS 


Fig.  56 — Showing  method  of  gathering  up  the  extrinsic  tissues 
in  order  to  get  rid  of  the  pucker  in  the  cornea. 

The  pupil  will  now  have  been  made  square, 
and  so.. large  that  no  difficulty  will  be  experi- 
enced in  reflecting  either  light  into  the  eye,  or 

108 


TECHNIQUE    OF    EYE    DISSECTIONS 

in  examining  the  inside  of  the  eye.  Care  must 
be  taken  not  to  lacerate  the  anterior  surface 
of  the  lens  when  the  iris  is  drawn  back  by 
the  pins. 

Putting  the  pins  into  the  cornea,  and  using 
them  as  levers  with  the  point  of  entrance  in 
the  cornea  as  a  fulcrum,  will  pucker  the  cornea 
considerably,  and  a  good  clear  fundus  cannot 
be  obtained.  This  is  easily  overcome.  Simply 
gather  up  all  the  tissues  surrounding  the  eye, 
force  them  backward,  and  hold  them  firmly 
with  the  fingers  of  the  left  hand.  (Fig.  56.) 
The  right  hand  is  then  free  to  handle  the  skia- 
scope  or  ophthalmoscope,  so  that  the  interior 
of  the  eye  may  be  thoroughly  examined. 

Another  way  to  prepare  an  eye  for  ophthal- 
moscopic  examination  is  as  follows:  Go  to  a 
slaughter  house  and  procure  a  beef  eye  from 
an  animal  that  has  been  killed  but  a  few  min- 
utes previously.  Placing  the  eye  immediately 
into  an  8  per  cent,  solution  of  cocaine  and 
leaving  it  there  for  about  an  hour  will  dilate 
the  pupil  to  such  an  extent  that  work  with  the 
ophthalmoscope  will  be  made  very  easy.  This, 

109 


TECHNIQUE    OF    EYE    DISSECTIONS 

as  indicated,  can  be  done  only  with  an  eye  that 
is  very  fresh. 

Still  another  way  to  see  the  interior  is  to  cut 
out  a  piece  of  the  sclerotic  about  the  size  of  a 
twenty-five-cent  piece;  then  pinch  up  and  tear 


Fig.  57 — Showing  window  cut  in 

sclerotic,  choroid, 

and  retina. 

out  the  choroid  and  the  retina  under  the  open- 
ing made  in  the  sclerotic.  (Fig.  57.)  Hold  the 
eye,  the  cornea  forward,  close  to  a  bright  light, 
and  the  image  of  the  light  will  be  seen  upon 
the  retina,  The  closer  the  light  is  to  the  eye, 
the  greater  the  illumination  will  be  in  the 

110 


TECHNIQUE    OF    EYE    DISSECTIONS 

interior  of  the  eye.  If  the  opening  or  "win- 
dow" is  close  enough  to  the  optic  nerve,  the 
optic  papilla  can  be  seen  easily.  And,  if  care 
has  been  taken  to  have  the  opening  made  mid- 
way between  the  two  branches  of  the  retinal 
artery,  the  entire  course  may  be  followed.  The 
direction  of  the  retinal  artery  can  be  deter- 
mined by  ophthalmoscopic  examination. 


Ill 


THE   LACKIMAL   DUCTS 

To  find  the  lacrimal  ducts,  cut  across  the 
cuter  and  inner  canthi  of  the  enucleated  eye, 
pushing  the  eye  forward  and  the  lids  back- 
ward. That  will  expose  the  conjunctiva  of 


Fig.  58 — Showing  how  pins  may  be  inserted  in 
lacrimal  ducts. 

112 


TECHNIQUE    OF    EYE    DISSECTIONS 

both  eyelids  and  eye,  and  also  show  the  con- 
junctiva! fornices.  On  the  upper  surface 
of  the  palpebral  conjunctiva,  and  near  the 
outer  can  thus,  will  be  seen,  upon  close  inspec- 
tion, a  number  of  minute  openings,  usually 
eight.  These  are  the  openings  of  the  lacrimal 
ducts.  Pins  or  straw  that  have  been  lubricated 
with  vaseline,  may  be  inserted  and  pushed 
into  these  openings  for  a  considerable  distance, 
and  the  course  of  the  ducts  then  can  be  traced 
easily.  (Fig.  58.) 


113 


THE  LACRIMAL  GLAND 

• 

THE  lacrimal  gland  is  easily  distinguished 
by  its  pink  appearance.  There  are  two  parts, 
inferior  and  superior.  The  gland  lies  directly 
over  the  eye  and  near  the  outer  angle  of  the 
orbit.  In  the  enucleated  eye,  it  will  be  found 
to  lie  near  the  outer  canthus  and  over  the 
eye.  The  gland  may  be  easily  dissected  out 
of  its  position  and  then  examined  more  closely. 
A  hand  lens  will  show  the  racemose  construc- 
tion of  the  gland.  If  the  gland  is  cut  in  two, 
the  racemose  construction  may  be  seen  even 
better. 


114 


THE  CAPSULE  OF  TENON 

To  dissect  the  capsule  of  Tenon,  it  is  neces- 
sary  to   carefully   remove    the    superficial  fat 


Fig.  59 — Enlarged  to  show  part  of  the  Capsule  of  Tenon 
blown  up.     (Page  116.) 

and  connective  tissue.  In  text-books  and  illus- 
trations, the  capsule  is  usually  shown  as  a 
definite  sac-like  membrane  of  considerable 
thickness,  with  all  its  parts  well  defined.  The 

115 


TECHNIQUE    OF    EYE    DISSECTIONS 

dissector  will  soon  find  that  the  capsule  is  not 
discerned  so  easily.  It  will  be  found  to  be  the 
thin,  semi-transparent,  fibrous  membrane  that 
surrounds  each  muscle,  as  well  as  the  "pos- 
terior two-thirds  of  the  eye,"  and  is  continu- 
ous anteriorly  with  the  ocular  conjunctiva. 
Portions  may  be  pinched  up  and  inflated 
through  an  inserted  blow-pipe.  This  will  help 
to  merely  demonstrate  its  location  and  parts. 
(Fig.  59.) 


116 


THE  SUPERIOR  OBLIQUE  MUSCLE  AND 
ITS  PULLEY 

AFTEE  the  lacrimal  gland  has  been  dissected 
away,  a  beginning  will  have  been  made  for  cut- 
ting away  the  fat  and  the  connective  tissue. 
The  first  thing  to  do  then  is  to  locate  the  su- 
perior oblique  muscle.  Try  to  keep  track  of 
which  part  of  the  eye  is  the  inner  side.  Hav- 
ing located  the  inner  side,  feel  along  the  top 
for  a  little  hard  eminence.  That  is  the  pulley. 
Begin  to  dissect  around  the  pulley,  not  through 
it,  and  then  follow  the  muscle  along  to  its 
origin;  do  not  separate  the  muscle  from  its 
origin.  When  the  superior  oblique  is  com- 
pletely freed,  the  action  of  the  muscle  may  be 
readily  demonstrated  by  holding  the  "ring" 
or  tendinous  pulley  with  the  fingers  of  one 
hand,  while  the  muscle  is  pulled  backward  and 
forward  with  the  other. 


117 


THE  OTHER  EXTRINSIC  MUSCLES 


WITH  the  dissection  of  Tenon's  capsule  and 
the  superior  oblique  muscle,  the  work  of  iso- 
lating the  other  extrinsic  muscles  will  have 
begun.  This  work  needs  no  directions  except 


Pig.  60 — Showing  the  tendinous  pulley  of  the  superior  oblique 
muscle  and  the  extrinsic  muscles. 

118 


TECHNIQUE    OF    EYE    DISSECTIONS 

a  warning  to  be  careful  not  to  injure  the  pul- 
ley of  the  superior  oblique,  and  to  be  careful 
not  to  cut  away  the  inferior  oblique.  The  in- 
ferior oblique  will  be  found  to  be  near  the 
"  pulley. "  If  the  dissection  is  not  carried 
too  close  to  the  origin  of  the  recti  muscles,  all 
the  muscles  may  be  kept  in  place. 

If  the  eye  has  not  been  previously  subjected 
to  the  hardening  influence  of  formaldehyde,  it 
may  be  put  into  a  5  per  cent,  solution,  and  at 
the  end  of  ten  or  twelve  hours  the  muscles 
will  have  become  rigid.  They  can  then  be  bet- 
ter studied,  and  may  be  kept  indefinitely. 
(Fig.  60.) 


119 


THE  THREE  TUNICS  OF  THE  EYE,  THE 
HYALOID  AND  ITS  ATTACHMENTS 

THIS  dissection  is  a  rather  difficult  one  to 
make,  and  requires  patience. 

Prepare  an  eye  by  placing  it  in  a    5    per 


Fig.  61— Cutting  through  the  iris. 

cent,  solution  of  formaldehyde  for  about  ten 
days  to  two  weeks.  Eemove  all  the  outside 
tissues.  Cut  away  the  cornea,  as  in  the  dis- 
section for  the  choroid  or  the  retina.  Loosen, 
as  far  back  as  possible,  the  sclerotic  from  the 
choroid.  Pemove  the  sclerotic  for  about  10 
mm.  back  of  the  equator  of  the  eye.  With  the 
tweezers  pick  up  the  pupillary  edge  of  the  iris. 
Using  the  small  pointed  scissors,  cut  through 

120 


TECHNIQUE    OF    EYE    DISSECTIONS 

the  iris.  (Fig.  61.)  Lift  either  one  of  the  cut 
edges  of  the  iris,  and,  with  the  sharp  edge  of 
the  scalpel,  gently  scrape  the  processus  zonu- 
loe  free  from  the  ciliary  processes,  cutting 


Fig.  62 — Scraping  the  ciliary  processes  free.     Showing,  also, 
the  choroid  cut  around  the  ciliary  ring. 

through  the  ciliary  ring  as  the  ciliary  pro- 
cesses are  detached  from  the  hyaloid  (pro- 
cessus zonuloe}.  (Fig.  62.) 

Great  care  must  be  taken  not  to  thrust  the 
point  of  the  scissors  into  the  hyaloid,  suspen- 
sory ligament,  or  vitreous,  else  the  lens  may 
become  detached. 

121 


TECHNIQUE    OF    EYE    DISSECTIONS 

After  the  iris  with  the  processes  has  been 
removed,  pinch  up  with  the  tweezers  a  fold  in 
the  choroid.  Make  an  incision  with  the  fine- 
pointed  scissors,  and  begin  removing  the  cho- 


Fig.  63 — Cutting  away  the  choroid. 

roid  to  within  about  5  mm.  of  the  cut  end  of  the 
sclerotic,  (Fig.  63.)  Care  must  be  taken  not 
to  penetrate  the  underlying  retina  while  mak- 
^g  this  part  of  the  dissection. 

.After  part  of  the  choroid  has  been  removed, 

specimen  will  show  the  three  coats  of  the 

c    3  in  layer-like  arrangement,  the  hyaloid  and 

122 


TECHNIQUE    OF    EYE    DISSECTIONS 

lens.  The  lens  may  now  be  cut  away,  if  the 
specimen  is  preferred  without  it,  Eemoving 
the  lens  before  this  time  is  unwise,  because  it 
acts  as  a  protection  to  the  other  tissues  while 
the  specimen  is  being  handled  during  the  dis- 
section. 

This  specimen  will  show  to  the  best  advan- 
tage if  it  is  suspended  in  a  jar  containing  a  5 
per  cent,  solution  of  formaldehyde.  Figure  64 
shows  the  specimen. 


Fig.  64 — A.  Optic  nerve.     B.  Sclerotic. 

C.  Choroid.    D.  Eetina.    E.  Hyaloid. 

F.  Lens. 

123 


INDEX 


Accessories,    ocular,    95 
Alcohol    as    a  preservative,    34 

of     running 


Capsule   of   Tenon,   115 

of   Tenon    and    conjunctiva,    116 
Cedar   oil,    60 


>0,   51,  86,  90 
half  of  eye,  49 
half,     removing    vitreous    from, 

49 

surface    of    lens,    55 
Aperture,       increasing       pupillary, 

106,     107,     109 
Aqueous    humor,    51 
Arteria    centralis  retinae,   43,  49 
Arteries,   ciliary,    72 

course  of  retinal,  111 
Artery    of   retina,    central,    43,    49 
hyaloid,   43 

B 

Beef  eyes,    26,    27 

Beginning   of  dissection  of  orbital 
contents,    97 

Benzine,    59 

Blood-vessels   of   retina,    106 

Blowing    through     blowpipe,     fold- 
ing retina  by,    81,    82 

Blowpipe,    folding  retina  by  blow- 
ing through,    81,   82 
glass,    35 

using    it    to   force    out   vitreous, 
78-81 

Body,   hyaloid,   41 

Boiling   crystalline  lens,    55,    56 

Books,    text,    23,    25,    46,    52 


Canal,   hyaloid,   43 

of   Petit,    35-37 
Canaliculi,     puncta,     papilla,     and 

nasal  duct,   locating,    92-95 
Capsule   of  lens,    33,    50,    54 

of   lens,   removing,   59 


.0,   51,   86,   90 
r,   50,   51,   86,   90 
Chemicals,    22,    23 
Chisel  and  hammer,  use  of,  99-101 
Choroid,    62 

and    sclerotic,    cutting    them 
away  for   isolating  retina,    83 
emptying,    69,   70 
for    dissecting    three    tunics,    re- 
moving, 122 

from  sclerotic,   for   dissection   of 
three      tunics      and      hyaloid, 
loosening,   120 
iridescence  of,  45 
loosening    from    corneo-scleral 

junction,    64,    65 
loosening  sclerotic  from,   64,   66, 

67,   68 
or  retina,    removing    cornea    for 

isolating,  62,  63,  64 
picking  up   retina    and,    30,    31 
preparing   eye   for   isolating,    62 
preserving  isolated,   72 
removing,   46 

removing  lens   from,    69,   70,    71 
scraping  sclerotic  from,    68 
separating  sclerotic  from,  27,  29 
Cilia    and    other    superficial    acces- 
sories,  95 

Ciliaris,    corona,    49,    51 
orbicularis,   49,   51 
retinae,  pars,   49 
Ciliary   arteries,    72 
nerves,    72 

processes,    27,    33,    49 
processes     free     from     processus 

zonuloe,  scraping,   121 
ring,    51 
ring,    cutting   ciliary,    121 


125 


INDEX 


Ciliary,    clarifying   lens,    58,    59 
Coats,    preparing    eye    for    dissec- 
tion   to    show,     in    situ,    the 
three,    120 
Cocaine,    109 
Color  of  processes,    50 
Concentric  layers  of  lens,   56,   57 
Conjunctiva  and  Capsule  of  Tenon 

116 

Conjunctival    fornices,    113 
Cornea,   epithelium  of,    52 

removing    it    for    isolating    cho- 

roid    or    retina,     62,     63,     64 

Construction     of     lacrimal     gland, 

racemose,   114 

Contents,    beginning    of    dissection 
of  orbital,   97-101 
dissecting   orbital,    97-105 
emptying    eyeball  of,    32,    33 
enucleating  orbital,    102-104 
material   for   enucleation    of   or- 
bital, 97 
preserving  of  hyaloid,   32,   33 

34,  36 
Cornea,    52 

and   sclerotic,    52 

layers    of,    52 

smoothing      it     for      ophthalmo- 

scopic  examination,   109 
Corneo-scleral      junction,       loosen- 
ing  choroid   from,   64,    65 
Corona    ciliaris,    49,   51 
Cortex  of  lens,   54,   59 
Course   of   retinal    arteries,    111 
Cross   section   of  optic  nerve,    48 
Crystalline  lens,   33,   49,  53 

lens  boiling,  55 

Cutting    away    sclerotic    and    cho 
roid    for    isolating    retina,    83 
ciliary  ring,    121 
cross   section  of  optic  nerve,   48 
eye   for   sagittal    section,    87-89 
eye  in  half,   38,   39 
iris    for    dissection   of   three    tu- 
nics,   120 

optic    nerve    longitudinally,    47, 
48 


Dehydrating    lens,    58,    59 
Demonstration  of  hyaloid,  etc.,  34 


Disc,   optic,   43 
Dishes,    Stender,    21 
Dissected   hyaloid,    33 
Dissecting   lacrimal    gland,    114 
nasal  duct,   papilla  and  puncta, 

92 

orbital    contents,    97-105 
of  hyaloid  membrane,    25,    33 
of    hyaloid,    method    of    prepar- 
ing  for,    26,    27 
of     orbital     contents,     beginning 

of,    97-101 
three   tunics,    removing   choroid, 

for,    122 

Dissection,    preparing    eye    for    in- 
terior, 38 
preparing  eye  to  show  the  three 

tunics  in  situ,  120 
of    three     tunics     and     hyaloid, 
loosening   choroid   from    scler- 
otic for,   120 
of  three  tunics,  cutting  iris,  for, 

120 

Duct,    material    for    dissecting    pa- 
pilla,   puncta,    and   nasal,    92 
papilla,    puncta    lacrimalia,    and 

nasal,  92 

Ducts,    meibomian    gland    and,    96 
lacrimal,    112,    113 


Emptying    choroid,    69,    70 

eyeball    of    contents,    32,    33 
Entrance  of  optic  nerve,   43 
Enucleated  eye,   104 
Enucleating  orbital   contents,    102- 

104 
Enucleation     of     orbital     contents, 

97-105 
of     orbital     contents,      material 

for,    97 

Epithelium    of    cornea,    52 
Equipment,    17-24 
Examination,    ophthalmoscopic, 

106 

preparing     eye     for     ophthalmo- 
scopic,   106-110 

smoothing    out   cornea    for    oph- 
thalmoscopic,   109 
Excavated    posterior    half,    46,    47 
sagittal,    90 


126 


INDEX 


Extrinsic    muscles,    other,    118 

muscles,     preserving,     119 
Eye,    anterior    half    of    the,    49 

contents,    emptying,    32,    33 

cutting    it    for    sagittal    section, 
87-89 

for    dissection    of    hyaloid,    etc., 
preparing,   26,    27 

in   half,    cutting,    38,    39 

interior    of,    38 

posterior   half  of  the,   40 


Half,    excavated    posterior,    46 
posterior,   40 
posterior,    excavated,    46 
preparing  eye  for  dissecting  in- 
terior,   38 

removing     vitreous     from     ante- 
rior,  49 

removing     vitreous     from     pos- 
terior, 41 

Hammer    and    chisel,    use    of,    99- 
101 


preparing    for    dissecting    inter-    Humor,    aqueous,    51 


ior,   38 


vitreous,    33 


preparing    it    for    dissection,    to    Hyaloid    and   attachments,    demon- 


show  the  three  tunics,  in  situ, 

120 
preparing      for      isolating      cho- 

roid,    62 
preparing    for    isolating    retina, 

74,   75 
preparing     for     ophthalmoscopic 

examination   of,    106-110 
preparing  for  sagittal  section  of, 

86 

sagittal    section    of,    86 
seeing   interior   of,    110 
vertical  section  of,   86 
cutting    window   in,    110 
Eyelids,    95,    105 
Eyes,    sheep   and  beef,    26,    27 


Fibres  of  lens,    56,  57 

network    of   vitreous,    41,    42 

Fluid,     perichoroidal,     40,     46 

Folding     retina     by     blowing     air 
through   blowpipe,    81,    82 

Forcing   out   vitreous,   using   blow- 
pipe in,  78-81 

Fornices,    conjunctival,    113 

G 

Gland,    dissecting  lacrimal,    114 

lacrimal,    114 

racemose    construction 
Glands   and   ducts,   meibomian,    96 
Glass  blowpipe,    35 
Glassware,    21 

H 
Half,  anterior,  49 

cutting  eye  in,   38,   39 


stration  of,    34 
artery,    43 
body,   41 
canal,    43 
dissected,  33 

membrane,    dissection    of,    25-33 
membrane     with     contents     and 

attachments     intact,     removal 

of,   25 
preserving    contents   of,    32,    33, 

34,    36 
preserving  three  tunics  and,  123 


Image,   retinal,    110 
Increasing   pupillary    aperture, 

106,    107,    109 

Inferior    oblique   muscle,    119 
Instruments,    21 
Interior   of   the   eye,    38 

of  the  eye,    seeing,    110 
Interior  section,  preparing  the  eye 
for  dissecting,  38 

Iridescent   choroid,    40,    43 

Iris,    49,    51 

and  lens,  removing,    <  6,  77 
and  processes,    removing,    121 
for    dissection    of    three    tunics, 

cutting,   120 

relation  between  processes   and, 
51,    52 

Isolated  choroid,  preserving,   72 

Isolating    choroid    or     retina,     re- 
moving   cornea    for,  *62-64 
choroid,  preparing  eye  for,  62 

Isolated  retina,  preserving,,  84,  85 


127 


INDEX 


Isolating    retina,    cutting    sclerotic    Loosening     choroid     from 


and  choroid  away  for,  83 
retina,    preparing    eye    for,    74, 

75 


Junction,    loosening    choro:d    from 
corneo-scleral,    64,    65 

K 

Knitting-needles,  use  of,   92-95 

L 

Lacrimal    ducts,    112,    113 
gland,    114 
gland,   dissecting,    114 


scleral    junction,    64,    65 
choroid    from    sclerotic,    64,    66- 

68 

choroid    from    sclerotic,    for    dis- 
section   of    the    three    tunit-s 
and  hyaloid,  120 
Lucidum,  tapetum,  45 

M 
Material,   19,  20,  21 

for    dissecting    nasal    duct,    pa- 
pilla,   and  puncta,   92 
for    enucleation    of    orbital    con- 
tents, 97 
Meibomian    glands    and    ducts,    96 


gland,   racemose   construction  of    Membrane    with    contents    and    at- 
tachments   intact,    removal     of, 

25 

Method  of   preparing   eye   for   dis- 
section of  hyaloid,   26,   27 
of    running    through    the    alco- 
hols,   58,    59 
Muscle,    superior    oblique    and    its 

pulley,   117 

Muscles,    other  extrinsic,    118 
preserving   extrinsic,    119 


114 

Lacrimalia,     nasal     duct,     papilla, 

and  puncta  92 
Laminated    structure    of    lens,    55, 

56 
Layers,  concentric  lens,  56,  57 

of    cornea,    52 

separating   outer  lens,   54 
Lens  and  iris,  removing,   75,   77 

anterior    surface    of,    55 

boiling  of,    55,   56 

capsule,    33,    50,    54 

clarifying,    58,    59 

concentric  layers  of,   56,    57 

cortex  of,   54,    59 

crystalline,    33,    49,    53 

dehydrating,    58,    59 

fibres,    56,    57 


N 


Nasal   duct,    canal:culi,    puncta, 
and    papilla,    locating,     92-95 
canaliculi,    puncta,    and    papilla, 

92 
canaliculi,    puncta,    and   papilla, 

material    for   dissecting,    92 
laminated    structure    of,    55,    56     Needles  and  pins,  use  of,  96,   106, 
nucleus  of,    55,    59  107,    108,    109,    112,    113 

use  of  knitting,   92-95 
Nerve,    cross    section    of   optic,    48 
entrance   of  optic,    43 
optic,    47 
optic,    cutting   it    longitudinally, 

47,    48 

separating    outer    layers    of,    54    Nerves,   ciliary,    72 
staining,    57  Network  of  fibres  in   vitreous,   41, 

Ligament,   suspensory,    33,   37  42 

Lines,     tri-radiate,     54-56  Nucleus    of   lens,    55,    59 

Locating    papilla,    puncta,    canali- 

culi,  and  nasal  duct,   92-95 
Longitudinally,      cutting     optic    Oblique,    inferior,    119 

nerve,   47,    48  pulley    of    superior,    117 

128 


posterior   surface    of,    55 
preparing    the,    53 
preserving    the,    57,    58 
removing  capsule   of,    59 
removing  it  from  choroid,   69-71 
removing  the,   51,    53 


INDEX 


Ocular    accessories,    95  Pins  and  needles,  use  of,  96,  106- 

conjunctiva  and  Capsule  of  Ten-  109,    112,    113 

on,   116  Pipette,    35 

conjunctiva     and     other     super-  Posterior  chamber,  50,  51,   86,  90 

ficial   accessories,   95  half   excavated,    47 


Oil,    cedar,    60 
Ophthalmoscope,   109 
Ophthalmoscopic  examination,   106 

examination,    preparing   eye    for 
106-110 

examination,   smoothing  out  cor- 

nea  for,    109 
Optic  disc,    43 

nerve,    47 

nerve,   cross  section  of,    48 

nerve,    cutting  it  longitudinally, 
47,    48 

nerve,    entrance   of,    43 

papilla,    111 
Ora  serrata,   49 
Orbicularis   ciliaris,    49,   51 


half  of   the   eye,   40 

half,     removing     vitreous    from, 

41 

surface    of    the    lens,    55 
Preparing    eye    for    dissecting    in- 

terior,   38 
eye    for    dissecting    hyaloid,    26, 

27 
eye    for    dissection   to    show    the 

three    tunics,    in    situ,    120 
eye  for  isolating   choroid,    62 
eye  for  isolating  retina,    74,   75 
eye    for    ophthalmoscopic    exami- 

nation,  106-110 
eye  for   sagittal   section,    86 


the    lens,    53 
Orbital     contents,     beginning     dis-    Preservative,    alcohol    as    a,    34 

section   of,    97-101  Preserving   extrinsic   muscles,    119 

contents,    dissecting,    97-105  hyaloid,     contents    and    attach- 


contents,  enucleating,  102-104 
contents,    enucleation   of,    97 
contents,    material    for    enuclea- 
tion of,   97 


ments,     etc.,     32-34,     36 
isolated    choroid,    72 
isolated    retina,     84,     85 
lens,   57,    58 
sagittal    sections,    89 
three    tunics    and    hyalo'd,     123 


Palpebra?  and  other  superficial  ac-    Processes,    ciliary,    27,    33,    49 
cessories,    95  and  iris>    removing,    121 

Palpebral    conjunctiva    and    other        color    of>    50 
superficial  accessories,    95 

Papilla,    nasal    duct,    and    puncta 
lacrimalia,   92 


pigment    cells    of,    49,    50 
relation  between  iris  and,  51  52 
zonular,    27,    34 
nasal    duct,     and    puncta    lacri-    Processus    zonuloe,    34 

malia,     material     for     dissect-         zonuloe    free    from    ciliary    pro- 
cesses,   scraping,    121 
Pulley    of    superior    oblique    mus- 
cle,   117 
Puncta    lacrimalia,    nasal    duct, 

and  papilla,    92 

lacrimalia,.    'papilla,     canaliculi, 
and  nasal  duct,   locating,    92, 
95 
lacrimalia,      papilla,      canaliculi, 


ing,  92 
optic,  111 
puncta,  canaliculi,  and  nasal, 

duct,   locating,   92-95 
Pars  ciliaris  retinse,  49 
Perichoroidal    fluid,    40-46 
Petit's    canal,    35-37 
Picking    up    choroid     and    retina, 

30,    31 

Pigment  cells  of  processes,   49,  5:j 
of   sclerotic,    46 
removal  of,    34 
Pinching   up    sclerotic,    27,    28 


and    nasal  duct,   material   for 
dissecting,    92 

Pupillary    aperture    increasing, 
106,    107,    109 


129 


INDEX 


R 

Racemose  construction  of  lacrimal 

gland,   114 

References,    23,    25,    46,    52 
Relation     between     iris     and     pro- 
cesses,   51,    52 

Removal      of     hyaloid      membrane 
with      contents      and     attach- 
ments   intact,    25 
of      pigment       from      processus 

zonuloe,    34 

Removing    capsule   of  lens,    59 
choroid,  46 
cornea    for   isolating    choroid   or 

retina,    62-64 
iris    and    lens,     75,     77 
choroid   for  dissecting    three   tu- 
nics, 122 

iris  and  processes,   121 
lens  from  choroid,   69-71 
lens     from     anterior     half     and 

other   parts,    51,    53,    54 
sclerotic    to    show    the    three 

tunics,    120 

the  retina  from  posterior  half,  44 
vitreous  from    anterior   half,    49 
vitreous  from  choroid,   70-72 
vitreous  from  posterior  half,  41 
Retina,    40-74 

blood-vessels    of,     106 
central    artery    of,    43,    49 
cutting   away   sclerotic  and  cho- 
roid   for    isolating,    83 
folding      it      by      blowing      air 
through  blowpipe,  81,  82 


Running  through  the  alcohols,   58, 
59 


S 


Sagittal    section,    cutting    eye    for, 

87-89 

section,    excavated,    90 
section    of    the    eye,     86 
section,    preparing    eye    for,    86 
sections,    preserving,    89 
Sclerotic      and      choroid,      cutting 
them    away   for    isolating    ret- 
ina,   83 

and    cornea,    52 

from    choroid,    for    d'ssection    of 
three      tunics      and      hyaloid, 
loosening,    120 
loosening   choroid  from,   64,   66- 

68 

pigment  of,    46 
pinching   up,    27,    28 
scraping    choroid    from,    68 
separating  choroid  from,  27,  29 
to  show  the  three  tunics,  remov- 
ing,  120 
Scraping    choroid     from     sclerotic, 

68 

processus   zonulce   free  from   cil- 
iary processes,    121 
Section    of   optic    nerve,    cross,    48 
cutting    eye    for    sagittal,    87-89 
preparing  eye  for  sagittal,  86 
sagittal,   86 
vertical,    86 


or  choroid,  removing  cornea  for  Sections,    preparing    eye    for     dis- 

isolating,    62-64  secting   interior,    38 

picking  up  choroid  and,   30,   31         preserving  sagittal,   89 

preparing     eye    for    isolating,     74,  Seeing   interior    of   eye,    110 


75 


preserving  isolated,    84,    85 

removing,    44 

straightening,     42,     43 

Retinae,   pars  ciliaris,   49 
Retinal    artery,    course    of,    111 

image,    110 

vessels,    40,    49 
Ring,    ciliary,    51 

cutting    c'liary,    121 

of  superior    oblique  muscle  ten-    Staining  lens,    57 
dinous,    117  Stender   dishes,    21 

130 


Separating   choroid   from   sclerot'c, 

27,   29,    64-68 

outer    layers    of   the    lens,    54 
Serrata,    ora,    49 
Sheep     eyes,     26,     27 
Skiascope,     109 
Smoothing    cornea    for    ophthalmo- 

scopic    examination,    109 
Superior    oblique    muscle    and    its 

pulley,    117 


INDEX 


Straightening    retina,    42,     43 
Structure    of    lens,    laminated,    55, 

56 
Superior  oblique  muscle,  pulley  of, 

117 
Surface  of   anterior  of  lens,   55 

of    posterior    of    lens,    55 
Suspensory   ligament,    55 


Tapetum    lucidum,    45 
Tendinous    ring    of     the     superior 

oblique  muscle,    117 
Tenon     and     ocular     conjunctiva, 

Capsule   of,    116 

Tenon's    Capsule,    115 
Text-books,    23,    25,    46,    52 
Three    tunics,     removing     choroid, 

for  dissecting,   122 
Tools,    21 

Tri-radiate  lines,   54-56 
Tunics,  in  situ,  preparing  eye  for 

dissection   to   show  the   three, 

120 
preserving    hyaloid     and    three, 

123 
removing  the    sclerotic,   to   show 

the   three,    120 


U 

Use  of  hammer  and  chisel,  99-101 
of  knitting-needles,  92-95 

Using  blowpipe  in  forcing  out  vit- 
reotis,  78-81 


Vena   vorticosa,    72 

Vertical   section    of  the    eye,    86 

Vessels    of   retina,    blood-,    40,    49, 

106 
Vitreous,    33 

network    of  fibres   in,    41,    42 
removing  from  anterior  half,  49 
removing     from    posterior    half, 

41 
using  blowpipe  to  force  out,   78- 

81 
Vorticosa,    vena,    72 

W 

Window,    in    eye,    cutting,    110 


Xylol,  59 


Zone    of    Zinn,     36,    37 
Zonular    processes,    27,    34 
Zonulii    Zinii,    36,    37 
Zonuloe    processus,    34 


131 


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